History is home to many stories of extraordinarily terrifying creatures. Known as cryptids, they exist on the very outer edges of the known world, inhabiting the liminal spaces between scientific certainty and folkloric imagination. These mysterious beings – from the famous North American Sasquatch or Scotland’s Loch Ness Monster, to the lesser-known Tikbalang of Philippine folklore, the Chupacabra legend from Puerto Rico, or the tale of the English devil dog known as Black Shuck – represent our fascination with the unknown and unexplained.
Added to that cornucopia of creepy cryptids is the astonishing story of the Mongolian death worm, a fearsome creature said to lurk beneath the shifting sands of the Gobi Desert.
But is it a product of overactive imaginations, a case of misidentification, or a savage monster biding its time? Let’s dig deep into the legend of the mysterious Mongolian sand worm.
What is The Mongolian Death Worm?

The Mongolian death worm is said to have razor-sharp teeth (Credit: Saminaleo via Getty Images)
The malevolent Mongolian worm, known in the local language as olgoi-khorkhoi, which translates as ‘large intestine worm’ on account of its size and colour, is described as a thick, blood-red segmented worm measuring anywhere from 60 centimetres to 1.8 metres (two to six feet) long. Some accounts say the worm is white-gray and smooth, only turning red when it’s angry. Others say it’s brown and scaly. Most versions of the story seem to suggest it’s most active after heavy rain.
This terrifying Gobi Desert killer worm is often reported to be armed with a terrifying pair of spike-like projections at its ends, as well as two, or even three rows of razor-sharp teeth. Local folklore paints it as a fearsome predator, spitting corrosive venom that can instantly kill a human or animal, and even destroy from a distance with a powerful electric shock.
The Story of Olgoi-Khorkhoi

Is the Mongolian death worm real? (Credit: © Philippe LEJEANVRE via Getty Images)
Such ‘death worm’ stories remained a closely-guarded legend in Mongolia until they captured Western attention in the early twentieth century, largely thanks to the writings of American paleontologist and explorer Roy Chapman Andrews. In his 1926 book On The Trail Of Ancient Man, he retold second-hand stories of this legendary Mongolian death worm he’d heard from officials in the country. However, he wrote ‘None of those present ever had seen the creature, but they all firmly believed in its existence and described it minutely.’
He included in his book a description of olgoi-khorkhoi from a former Mongolian prime minister, who’s thought to have said ‘It is shaped like a sausage about two feet long, has no head nor leg and it is so poisonous that merely to touch it means instant death. It lives in the most desolate parts of the Gobi Desert.’
The Hunt for this Mongolian Sand Worm

Expeditions to the Gobi Desert have all returned empty-handed (Credit: mantaphoto via Getty Images)
Andrews’ accounts and subsequent retellings in books, newspapers, and documentaries brought the Mongolian death worm into the global imagination. From the middle of the twentieth century, adventurers, cryptozoologists, and thrill-seekers alike have attempted to track it down…
Ivan Mackerle’s Expedictions
In the late 1980s and early 1990s, Czech cryptozoologist Ivan Mackerle organised multiple expeditions to Mongolia in search of the Gobi Desert killer worm, interviewing local witnesses and trekking across remote desert regions. He deployed various experimental methods, including vibration-generating devices inspired by Frank Herbert’s sci-fi novel Dune, and even small explosive devices, in attempts to lure the worm from beneath the sand, but all to no avail.
Post-1990 Expeditions
Following a change in Mongolia’s government in the 1990s, others went on the search for olgoi-khorkhoi. In 2005, members of the UK-based Centre for Fortean Zoology (CFZ), led by zoologist Richard Freeman, ventured into the Gobi on their own quest to find the Mongolian worm. Much like Mackerle, Freeman interviewed eyewitnesses, investigated alleged sightings, and scoured remote areas where locals claimed to have encountered the creature. Though they also emerged empty-handed, their efforts captured media attention, reinforcing the Mongolian death worm’s status as a prominent cryptid in Western circles. In 2009, another of the expeditions was by New Zealand entertainment reporter David Farrier, who, like the rest, didn’t find any evidence of the enigmatic Mongolian sand worm.
Is it a Bird, is it a Plane…

Did locals identify this sand boa as the Mongolian death worm? (Credit: reptiles4all via Getty Images)
…or is it a snake? Several theories suggest the Mongolian worm might actually be a misidentified snake, or desert-dwelling reptile. It’s postulated that the death worm could be a limbless underground reptile known as a worm lizard, or it could be a venomous snake.
In 1983, a tartar sand boa, a species of non-venomous snake endemic to the region was shown to locals who claimed to have seen olgoi-khorkhoi, and positively identified it as the same animal.
But this was by no means the end of the theories, and indeed despite such explanations, many other theories persist. One such idea posits that the worm is in fact a surviving species of dinosaur which has adapted to the harsh Gobi desert environment over millions of years. Still other theories speculate it could be a creature from another world.
Dune & Dusted

What secrets lie within the Gobi Desert's millions of years of history? (Credit: Anton Petrus via Getty Images)
Despite the wealth of stories and alleged sightings, hard evidence of the Mongolian death worm’s existence remains tantalisingly out of reach. No verifiable specimens have ever been recovered, nor have there been any confirmed photographs.
Nevertheless, the possibility of an undiscovered creature lurking in the Gobi’s remote dunes continues to captivate. Most argue that the worm is nothing more than a fantastical construct of nomadic folklore, or a common-desert snake simply trying to mind its own business. Yet, to this very day, many remain convinced that lurking beneath the shifting sands lies a deadly enigma – a creature both mysterious and lethal, poised beyond the reach of science, waiting silently for its moment to strike.