Creatures That Could Be Aliens

Here are some creatures that could be aliens!

March 1, 2023・

19 min read

For centuries, humans have gazed at the stars, wondering what life could lie beyond the atmosphere. But even here on Earth, some creatures are so strange, unique or downright terrifying, that they’d look more at home on Mars.

From cute little critters with astounding abilities, to blood-curdling monsters at the bottom of the ocean, let’s check out some creatures that are completely out of this world.

Walking Plants

The Leaf Sheep is a sea-slug with a punk-rock haircut, an impossibly cute face, and a space-age power that’ll blow your mind.

This plant-type Pokémon-like-creature spends its time crawling around the ocean, grazing on fields of algae. Only, when it chomps down on the greenery, it also absorbs their chlorophyll, a component that allows plants to photosynthesize.

Instead of wool, the sea sheep’s back is covered in leaf-like appendages called Cerata, and they work just like the real-thing. Storing chlorophyll, they allow nutrients and energy to be absorbed from sunlight like a moving solar panel, turning the Sea Sheep into a plant-animal hybrid.

The Sea Sheep’s rare ability to photosynthesize makes it an incredibly unusual cross between plant and animal; and coupled with its appearance, it makes it the type of creature that you’d to expect to find on a whole other planet.

Telescopefish

The telescope fish is the deep sea’s scariest predator. The fish looks like a mad-alien-scientist, and you can just imagine him jetting across the solar system in a UFO.

The telescope fish gets its name from the tubular eyes that stick out if its head, their unique shape giving the fish powerful vision that’s hypersensitive to light.

Despite swimming up to 10,000 feet deep, the 7-inch-long telescopefish can detect small amounts of light coming from the ocean’s surface. As a result, the telescope fish hunts by floating vertically through the ocean and looking up, allowing it to see the silhouettes of its prey as they swim above it.

If the hunt is successful, the telescope fish’s unique jaw allows it to swallow prey larger than its entire body, thanks to its large, expandable stomach. While this alien-looking fish’s eyes might not quite be bigger than its belly, they’re certainly pretty close!

The Antarctic Scale Worm

The Antarctic Scale Worm looks like a beautiful golden creature, floating through the water like a designer purse.

Its scales look like soft, 24 Karat gold, and it’s a reminder of how beautiful life on Earth can really be, that is, until you get within biting distance. Truly horrifying.

The worm's head is actually a retractable throat that’s usually folded into its body. Its hunting tactics are straight out of a Sci-fi horror flick. A curious little animal swims up to a beautiful golden alien to check it out, but when it gets too close, the Scale Worm’s throat bursts towards them, snapping them up with its razor-sharp teeth.

The Scale Worm is nature’s mullet; party at the back, evil devil-spawn at the front. Thankfully, the worms are only found in Antarctic waters, and they’re pretty rare, meaning that we don’t know much about their breeding habits, or what they eat.

Aliens From The Depths

A long time ago, in a galaxy known as the Milky Way, a cave near Mangalia, Romania was sealed up by the shifting of Earth’s crust, trapping a little society of animals together for 5.5 million years.

In 1986, a team of construction workers accidentally drilled into this place, now known as Movile cave, discovering a small space filled with deadly toxic gasses, intense heat, and 33 completely new species of animals. The creatures had made themselves at home in a pretty unhomely place, evolving to survive the cave’s extreme conditions over millions of years.

This means that they evolved in a totally different world to other life on earth. In Movile cave, some of the creatures are transparent and most of them are completely blind, their eyes disappearing over millions of years as they developed longer antennae and arms to feel their way around in the pitch-black.

Movile is largely filled with sulfuric water, but most of these bugs thrive in little pockets of air that appear in the cave’s walls and ceiling. The air in these pockets is composed of usually-deadly amounts of carbon dioxide, methane, hydrogen sulfide, and ammonia, and is only 10% oxygen; half the oxygen level on Earth’s surface.

Yet, the tough little bugs have evolved to survive these conditions; able to swim, crawl and hop around despite the cave’s toxic air. In fact, the sulfur and methane present in the cave is central to the food chain: those chemicals are fed upon by bacteria and fungi, which in turn feed the cave’s herbivorous occupants, who then feed the cave’s predators!

Some scientists believe Movile cave might unlock the secrets of alien life elsewhere in the universe, allowing us to understand how creatures can thrive in places usually considered to be inhospitable.

Thermal imaging has shown that there are cave networks on Saturn’s moon Titan, for example, and if parts of these caves are cut off and protected from the harsh conditions on the moon’s surface, alien life might’ve been able to evolve.

The Blob

When I was a kid, all my teachers used to call me ‘brainless,’ but maybe that isn’t such a bad thing. Case in point: Physarum Polycephalum, a type of Slime Mold, which despite having no eyes, ears or brain, exhibits the possession of memory, solves basic math problems, and navigates mazes. Pretty impressive for a brainless creature.

In one experiment, Japanese scientists at Hokkaido University recreated a map of Japan in a petri dish, placing flakes of food down in certain positions to represent Tokyo and its surrounding cities.

Within hours of being placed on the dish, the Slime Mold, composed of thousands of tiny, amoeba-like organisms working together as a single unit, had sent tendrils of slime towards the food, almost perfectly recreating Japan’s trainline-routes in the process.

Working out the most efficient way to connect these cities took human engineers over a century, but the Slime Mold solved the problem in just over a day.

The fact that slime mold can solve problems and store basic information without neurons or a brain has stumped scientists around the world, proving how little we know about life on our own planet.

If we meet aliens one day, they may not necessarily be humanoids with giant brains, they could have a totally alien type of intelligence that we can’t even imagine, just like Slime Molds.

Pyura Chilensis

If aliens really live on earth, then they’ve been doing a pretty good job of disguising themselves, and no creature is better disguised than the Pyura Chilensis.

At a glance, the Pyura looks just like a big rock until you cut it open, revealing its fleshy, red insides. Images of Pyuras look totally alien, and the idea of a rock with organs is absolutely sci-fi horror territory.

It’s one of the only living rocks that isn’t called Dwayne, but unfortunately, the Pyura is all Rock and no Roll, belonging to a class of immobile animals called sea-squirts.

The Pyura’s outer layer is known as its ‘tunic,’ a cellulose-like material that forms an exoskeleton, protecting the creature as it attaches to a rock and feeds, sucking in seawater and filtering out the algae and microorganisms to eat for dinner.

But if Pyura Chilensis are undercover aliens, they’re not doing a great job. In Chile, their insides are eaten as a delicacy, and some people even use the rock’s meat as an aphrodisiac.

Space Bears

Everybody loves a superhero, and our next creature is an animal with some real-life superpowers. The Tardigrade might not wear a cape and spandex, but these little creatures are practically invincible.

At 0.04 inches long, these creatures might not seem so tough, but they can survive temperatures ranging from 300 degrees Fahrenheit, to -457. If a tardigrade is completely dehydrated it’ll shrivel into a tiny ball, carrying out a process called vitrification that temporarily turns the fluid in its cells into glass.

Tardigrades have been known to survive in this state for over 10 years, and if they’re reintroduced to water decades later, they’ll spring back to life like a microscopic zombie, their cells reverting back to normal.

All of that’s pretty cool, but what makes them even more alien is the fact that they can survive in space. In 2007, a Russian space mission took some dehydrated Tardigrades up into Earth’s orbit and exposed them to the hard vacuum of outer space for 10 days.

The tardigrades were faced with temperatures of -455 degrees Fahrenheit and a vacuum that would kill a human within seconds. Despite all this, within an hour of being brought back to Earth and rehydrated, the tardigrades were scrambling around like nothing had happened, making them the only known creatures capable of surviving the vacuum of space.

This wasn’t a one off. In 2019, an unmanned Israeli spacecraft carrying tardigrades crash landed on the moon after a total failure of its main engine. Some experiments have shown that the Tardigrades probably wouldn’t have survived the impact.

However, the co-founder of the Israeli space organization was adamant that they’re still alive, meaning that a little group of moon bears might be crawling around up there right now. If that’s the case, then these tardigrades really are aliens, becoming the first known creatures to live off of the planet!

Ancient Aliens

The Crinoid fossils may look like cheap props from a sci-fi film, but they are an ancient creature that swam around 300 million years before the dinosaurs.

Their bulbous heads and curling tentacles are terrifying to look at, and the fossils have been used as inspiration for creatures in movies, like the Sentinels in The Matrix and the face huggers in Alien! Crinoid fossils are so old, scientists aren’t even certain what the creatures evolved from.

Judging by their appearance, they could've come from outer space. But, of course, that’s pure speculation. The descendants of crinoids, however, are still swimming around today, showing us what ancient crinoids would have actually looked like, and how they moved around the ocean.

If these feathery friends make the crinoid fossils seem less scary, just remember that the largest crinoid fossil ever found was 130ft long! In case you thought the current oceans were scary enough!

E.T. the Extinct Terrestrial

While the creatures living on Earth today can be pretty strange, as we just saw with the ancient crinoids, they’re nothing compared to the creatures of the ancient past. The seas of the past were occupied by truly alien-looking creatures like Terataspis Trilobite, gigantic bugs with spine-covered backs, snaking antennae, and 27-inch-long bodies.

These monsters really did exist, crawling along the ocean floor 397 million-years-ago. In 2016 Nasa released a new set of images from Mars, and conspiracy theorists spotted a couple of rocks in the background that they theorized were Trilobite fossils.

The blurry “evidence” is pretty unconvincing, but it shows that when you find a creature as freaky as a Terataspis Trilobite, it sends some people’s minds heading right for the stars.

Even stranger than the trilobite is the Hallucigenia, an insane ancient ‘sea-worm,’ sporting neck-tentacles, spiky spines and a ton of teeth in all the wrong places. But don’t freak out too much, because these little guys were only half-an-inch long.

When scientists first found Hallucigenia fossils in the 1970’s, they couldn’t even work out which way up the Hallucigenia walked, or where its face was. After prodding and poking at the fossils for decades, they started to understand the wacky world of the Hallucigenia, leading to animations and drawings that show just how alien this creature really was.

As for its neck-tacles? Scientists still aren’t sure what they did but I reckon they could be used to bust out some pretty sweet dance moves.

Scientists might’ve cracked the code on the Hallucigenia, but some fossils are so strange that they still remain a mystery. Take the Tully Monster, discovered by amateur fossil collector Francis Tully, for example. Despite more than 100 Tully Monster fossils being uncovered since 1958, scientists still don’t know whether the creature was a type of worm, mollusk, eel or fish.

We do know that it was a sea creature, it lived 300 million years ago, and it was really, really freaky. Its eyes were attached to stalks, jutting out the top of its 14-inch-long body, and its mouth sat at the end of a long stretching neck, ready to grab at its prey.

Nobody knows for sure what it evolved from, or evolved into, and the mystery surrounding the Tully Monster has led to a wave of conspiracy theories. Some people think it’s an alien creature, others think it’s an ancestor of the Loch Ness Monster.

Ink-Redible Octopi

For some people, the idea of aliens currently living on Earth is ridiculous, but that doesn’t necessarily mean that they haven’t ever visited the planet. Get ready to put your tin-foil hats on, because according to a team of 33 researchers, Octopi are aliens that were brought to Earth by meteors.

In a paper published in the science journal, ‘Progress in Biophysics and Molecular Biology’, a group of scientists argue that 540 million years ago, the earth was struck by a comet, carrying either fertilized octopus eggs from another world, or an alien virus that infected a group of primitive squid, causing them to mutate and evolve into the modern octopus.

These claims might seem insane, until you look at all the tenta-cool things that octopi can do. They can camouflage themselves, spray ink, fit through tiny spaces, and regrow lost limbs!

The ocean is octo-pied by 289 species of octopus, and some of them are super intelligent, known to solve complex puzzles, and unscrew the lids on containers to access food.

The scientists behind the paper state that these adaptations seemingly evolved very suddenly, and the octopus’ ancestors show no signs of having any of these traits. So, maybe an asteroid-riding alien squid monster is responsible for Octopi as well as Crinoids? Those creepy fellows really got around, if so.

Unfortunately, the controversial paper received very few supporters in the wider scientific community, given that it was almost purely theory, with no real evidence to support the extraterrestrial octopi claims.

Mouth Invaders

With all the abductions, invasions, and body-replacing imposters, the extra-terrestrials in pop culture don’t always come in peace. Luckily, these terrifying types of monsters are just works of science fiction, right? Nope.

Cymothoa Exigua is a real-life body invader, also known as the tongue-eating louse. But the louse doesn’t just eat tongues, it’s way worse than that. The louse preys on fish, entering their bodies through the gills and severing the blood supply to their tongues, making them rot and fall off.

The parasite then replaces the tongue, living inside the fish's mouth and acting as a fully functional, living prosthetic. This allows the fish to go on living, swimming around and looking for food while the louse drinks its blood or mucus.

When their fish dies, these little squatters just crawl out and search the ocean for a new host to live in. I’ll bet their fish of choice is a brand-new tuna; eight bedrooms, four bathrooms and a hot tub in the backyard.

Comb Jellies

When you travel down to the bottom of the ocean, it starts to look more like deep space than the deep-sea. With creatures like the sharpear enope squid, which lives 3,000ft below the waves, it’s not hard to understand what I mean.

But some of the most mind-blowing deep-sea creatures of all are comb jellies; mysterious invertebrates that live up to 23,000 feet below the surface. There are over 100 known species of comb jelly, and each one is just as alien as the next.

They can be dark red, translucent or a dazzling blue, but almost all of them are covered in what look like flashing multicolored lights, like UFO’s or gaming keyboards.

Comb Jellies have been swimming around for at least 500 million years, but they have space-age abilities. A deep-sea camera caught this footage below, for example, over 3,000 feet below the Indian Ocean.

This symmetrical shape might look like a CGI spaceship, but it’s actually an incredibly rare type of black-pigmented comb Jelly with the ability to change its form in seconds, morphing into a ghostly figure with arrays of colored lights that appear to twinkle.

This creature’s ability to shapeshift is unique among comb jellies, and scientists theorize that it uses the ability to feed, catching prey in its blanket-like body, or possibly to scare off predators.

Despite its appearance, this comb jelly isn’t actually covered in a set of rainbow LEDs. Almost all comb jellies are covered in microscopic hairs called cilia that they use to paddle through the water. As light passes through the cilia, they act like prisms, breaking the light apart into separate wavelengths of color, giving the appearance of individual, colored lights.

As incredible as it all looks underwater, if a comb jelly ever ends up on dry land, they lose their mysterious appearance due to the much lower pressure compared to what they’re used to in the deep sea, looking more like a big puddle of hand sanitizer.

The Mantis Shrimp

What do you get when you cross the eyes of an alien, the face of a prawn and the fists of Mike Tyson? The mantis shrimp.

Humans only have 3 color photoreceptors in their eyes, whereas mantis shrimp have 16, meaning that they can differentiate colors at a level we can’t even imagine. Their eyes are by far the most complex visual structure ever discovered on earth, even able to detect UV light and polarized light.

With the ability to see forms of light that are invisible to the human eye, mantis shrimp present an intriguing possibility: there could be alien life out there, or even on our planet, that exists within frequencies of light, or even types of matter, that our limited senses are totally unable to perceive. There could even be an invisible alien sat next to you right now.

If that idea scares you, it might be time to learn from the mantis shrimp’s other amazing talent. Despite being just 6 inches long, they can use their club-like claws to hit their prey with the same velocity as a .22 caliber rifle, firing off punches at over 50mph.

Fishermen affectionately call mantis shrimp ‘Thumb-Splitters,’ and the creature's uppercut is so powerful that it vaporizes the water around it, resulting in super-heated bubbles approaching the temperature of the surface of the sun!

Mantids

Let’s keep the Mantis train rolling, moving on to the mantis shrimp’s namesake, the praying mantis. Back in the 90’s, there were, admittedly, questionable reports of people being abducted by Mantis-Aliens; 7 foot tall Mantids that could shapeshift, using alien technology in their UFO’s to appear more human and fit into their surroundings.

Of course, seeing as it was the 90’s, all they really needed to fit in was a tracksuit and a pair of dungarees. But similarly, in parts of Southern Africa, the San people tell ancient myths about a trickster god called Iaggen, a praying mantis that could shapeshift into ordinary San people and mimic other animals.

A small group of conspiracy theorists believe that these myths are real sightings of the same Mantis-Aliens, theorizing that these creatures have preyed on Humans for centuries. Obviously, the idea that Mantids belong to a race of shape-shifting aliens is pretty insane, but the origins of the stories become slightly more understandable when you look at some of the vert real mantids living on Earth.

Take the Orchid Mantis, a bright pink critter that mimics a flower, luring plant-eating bugs and pollinators towards it before striking.

The Orchid Mantis might be too pretty to be an evil alien overlord, but the Empusa Fasciata has all the characteristics to be the one. The species has tall, towering crown extensions, making them look extra-terrestrial.

Its thin green body and purple appendages look just like a flowering plant, and it’s easy to see how ancient cultures and religions could worship these masters of disguise as shapeshifters.

To most of us, these mantids prove the wonders of evolution, but to the conspiracy theorists, they’re just proof that the Mantis-Aliens have already infiltrated Earth, disguising their little cousins as plants and flowers to spy on us, gathering intel on the human race until it’s time to strike.

The Noodle Hop-Hop

Believe it or not, this next creature isn’t an alien from Star Wars, a rat from a parallel universe, or the winner of a ‘re-design the mouse’ contest. The Jerboa is a real creature that’s 60 percent tail, forty percent leg, and 100 percent ridiculous.

The Kazakh people of Northern China call the Jerboa, ‘Noodle hop-hop,’ and it’s easy to see why. It might look like a potato on stilts, but the Jerboa’s long springy legs allow them to flee predators at up to 15 miles per hour, and evasively leap 10 feet into the air with a bit of practice.

If they can jump that high on Earth, imagine how high they could get in zero gravity!

Bigfin Squid

Before we started looking out to the stars, people were terrified of the mysteries that lay underneath the ocean. Tales of sea monsters have occupied humanity for centuries, and in 2007, a team of scientists captured some footage of a real-life example.

The monster is a Bigfin squid, swimming 7,800 ft below the Gulf of Mexico. Its tentacles are 26 feet long, held out to the squid's sides before dropping at right-angles down to the depths below, swinging around like demonic puppet strings.

Scientists believe that the squid might drag these tentacles across the depths, grabbing any edible organisms that it encounters and pulling them up to its jaws. It’s just like the claw machine at the arcade, although something tells me that the Bigfin rarely drops its prey.

Sightings of the creature are incredibly rare, but when one occasionally gets spotted by a submarine at the bottom of the ocean, surrounded by particles that shimmer like stars, the Bigfin squid really does look like an alien monster, floating through the cosmos.