- A lot of people find worms gross, primitive, boring even.

But monstrous?

I didn't think so.

I even had one as a pet in grade school.

Don't judge me.

But alas, humans can't just leave the digesting tubes in peace.

Nope, we have to have monster death worms, like graboids, sand worms, and Precambrian worms, But those are all modern examples.

Long before, two particular kinds of killer worms loomed large and global folklore and were recounted in history books, the Indus worm and the Mongolian death worm.

So how can we account for the purported existence of these creatures?

What makes us want to turn the lowly worms scary, or are there actually enormous terrifying worms out there roaming the earth?

You're about to find out.

I'm Dr. Emily Zarca, and this is Monstrum.

By my definition, the death worm of myth fiction and folklore refers to any soft bodied, limbless invertebrate monster or cryptid that moves by crawling, lives at least partially under sediment, and poses a threat to humans.

The most ancient death worm on record is the Indus worm.

In the fifth century BCE book Indica, Greek physician and historian Ctesias wrote that the only animal found in the Indus River was a creature that resembled the larva that live in fig trees, but on a much larger scale.

He described a behemoth white maggot with a girth so wide that a ten-year-old child could hardly embrace it, and a length spanning seven cubits long, which by the way, is close to 3.2 meters.

So this thing was huge.

He stated that this giant worm, called the skolex by his Greek contemporaries, lived obscured in the mud, coming out only at night to hunt.

According to his account, the creature had only two teeth in its jaw, one above, one below.

It used these teeth to grasp horses, oxen, and camels, dragging their bodies into the water to drown before consuming everything but the intestines.

Ctesias wrote that although a difficult endeavor, these worms could be captured.

A young goat or lamb would be changed to a large hook and used as bait.

He also claimed that if one was killed and left out to dry, it would secrete a highly flammable oil.

Other legends say that the oil was used for a flame thrower weapon akin to the Greek fire used by the Byzantine empire to torch enemy ships.

A couple of hundred years later, another famous Greek philosopher, Ptolemy, also wrote about a giant worm of the Indus, largely repeating Ctesias' description, even down to the part about it being seven cubits tall.

It wasn't until the 19th century that scholars increasingly attributed these stories of the Indus worm to exaggerated accounts with crocodiles or alligators, which could make sense, given that estuarine crocodiles are common across India and Southeastern Asia, with a habitat that spreads into the Solomon Islands and Northern Australia.

Their widespread numbers can be accounted for in part because they can live in marine, brackish, and freshwater habitats, and they can even cross the open ocean.

And yes, they are known to inhabit rivers.

Perhaps this common predator, which reaches anywhere between three to five meters in length when full grown, is the true template of our death worm of the Indus river.

But wait.

There is another proposed explanation for the monster, one rooted in the religious history of the Indus River Valley.

In 1852, German scholar Christian Lassen suggested that the worm story was of mythological origins, serving as an allegory for the gift of fire given by the serpent god of the region, which Ctesias had misinterpreted as a real creature.

This theory gained support when we consider all the ancient carved and painted figures of snakes and cobras, including representations of the semidivine half Cobra, half human Naga that had been discovered in the Indus Valley.

These artifacts suggest that serpents were indeed associated with the religious traditions of the area.

The Naga were said to live underground, could blast flames, and possessed magical fire.

Moreover, in the Hindu and Buddhist traditions, the Nagas, like the Indus worms, are associated with water.

And what if the two top and bottom teeth of the worm are really just distortions of a snake's fangs?

I'm not sure we'll ever know the real origin of the Indus worm tales.

Stories of the creature largely faded into obscurity after the 19th century, but another killer worm quickly rose up: the Mongolian death worm.

Already a creature of regional lore, American Explorer and naturalist Roy Chapman Andrews revealed the Mongolian death worm's terrifying form to a Western audience in 1926 in his expedition accounts of the Gobi Desert.

Andrews wrote that while he was obtaining permissions for an expedition, the prime minister of Mongolia asked him to capture a specimen of the legendary beast.

Andrews claims that Mongolian locals told him the monster is shaped like a sausage, about two feet long, with no head, tail, or legs.

It is so poisonous that touching it or even just looking directly at it would mean instant death.

In 1932, Andrews clarified that the creature was probably an entirely mythical animal.

As the legend grew, so did the length of the beast.

Current accounts give the creature's length as between 0.5 and 1.5 meters, and the legendary red worm now possesses a deadly acidic venom, and is even capable of producing electricity.

In a really bizarre entry into death worm lore, one noted scientists paid homage to the legendary monster with a prank in an otherwise very serious journal.

In 1956, Charles Bogert coauthored a monograph about the Helodermatidae lizard family that referenced a new species of lizard Cobra hybrid shaped like a sausage with a speckled band pattern, and fangs in both upper and lower jaws.

It is named as the sampoderma allergorhaihorhai, and lives throughout India, or possibly Baker Street, England.

Yes, in addition to clearly linking the fictional lizard with the Mongolian death worm, there's a Sherlock Holmes reference.

Why did it renown scientists play such a practical joke, and how did it make its way into a legitimate scientific publication?

Well, you'll have to ask the peer reviewers about that last part, but reportedly, Bogert just wanted to rile up his uptight colleagues.

The 20th century continued to yield more fictional monstrous worms into pages and films of science fiction.

Frank Herbert's wildly praised Dune series quickly captured the imaginations of millions of readers and massive critical acclaim.

It also gave us Kyle McLaughlin.

(dramatic music) Center to the story are the sand worms, a species of hundreds of meters long, worm-like monsters with thick, scaled, orange skin.

A biography of the author written by his son notes that many mythological tales inspired the creation of Dune, including dragon myths.

Throughout history, dragons have been known by many names, including the old English wyrm, which is actually where we get the name for the very un-dragonlike invertebrate worm.

And while the sand worm is also associated with the religion of Arrackis' locals, and can be captured with hooks and mind for its spice rather than a flammable oil like the Indus worm, similarities between those two death worms are interesting as well.

Herbert's books are vague about the inner most biology of the sand worm, perhaps intentionally, choosing to focus on how it impacts the environment of Arrackis and people who encounter it.

Although the creature most physically resembles earthworms, in the real world, allelid worms require moisture to survive, which is very different from the dry desert of Herbert's alien planet.

You would think that the desert habitat and physical similarities of Herbert's sand worm, including that it is trailed by lightning, would indicate that legends of the Mongolian death worm inspired the author.

Yet, he attributes the sand dunes of Florence, Oregon as his primary inspiration.

Although, Herbert did conduct extensive research on deserts and the religions in desert environments.

He also drew parallels between the brutal shifting sands of the desert with the equally merciless sea.

The similarities made in the book between the sand dunes and the ocean call to mind the real marine worms that mirror many elements of the sand worm.

Bobbit worms.

Distributed across the shallow marine and intertidal environments of the Atlantic, Indian, and Pacific oceans, bobbit worms are largely mysterious, and pure nightmare fuel, if you ask me.

What we do know is that they can grow up to three centimeters in diameter and reach a length of three meters.

They live in burrows, which they use to hide from their prey before launching upwards to violently seize unsuspecting marine critters in their jaws and drawing them back underground.

Yes, jaws.

Worms with jaws, who are real.

Yeah, these seem like the real, live versions of death worms.

Let's not forget Tremors, a franchise I hold near and dear to my heart, whose subterranean worm-like graboids prowl the sands of Nevada.

The special effects artists of the film stated in a 2014 interview that the best material for monsters comes from nature.

They cite the snapping turtle's jaws as the inspiration for the graboid's mandible.

Although again, these seem more like bobbit worms to me.

Graboids are pure fiction.

Although we do live on a planet with worm lizards, usually limbless, burrowing lizards that resemble earthworms, though they possess rudimentary eyes and eardrums, and are capable of identifying some low frequency vibrations, which just so happens to remind me of a famous fictional species of death worms.

(monster growling) To add to your mental file of real worm-like things that could star in horror movies, we have gray-brown, limbless, burrowing lizards, slow worms.

And then there are the giant earthworms.

Scientists theorize that giant terrestrial earthworms once roamed parts of our world, and some still do, like the giant gippsland worm of Australia, which can reach up to three meters in length.

That being said, these creatures are much skinnier and lack the killing power of your typical death worm monsters.

Australia also happens to have a few species of burrowing beach worms that can grow quite long, because of course they do.

So we have thousands of years of worm-like monsters that inspire monster legends, science fiction, and horror stories, but what makes these worms scary besides their giant size?

Some people do suffer from scoleciphobia, the irrational fear of worms, usually associated with the perception that they indicate poor hygiene or dirtiness.

And worms do love the dirt.

More broadly, worms, grubs, maggots, all limbless, faceless, wriggling things that can cause us harm.

Worms can contaminate our food.

They can enter our bodies.

They help eat dead things, even us.

Perhaps the persistent construction of death worms is partially an extension of this uneasiness about invertebrates and a fear of what lies below our feet every day.

Is there a real venomous monster worm buried somewhere in the Gobi Desert or the Indus River, waiting for us to discover it?

If you ask me, probably not, but when we actually start exploring that possibility, we are confronted with the other very real creatures that wiggle, slither, and creep their way across our planet.

And sometimes, truth is stranger than fiction.