Frank Herbert, the author of Dune, has not invented anything! We all remember the big sand worms of this science fiction saga. Mongolia has nothing to be ashamed of in comparison to it, since it has its own big worm: the olgoi khorkhoi, which means “large intestine worm”.

This creature is also called “worm of death” and is supposed to live in the most remote and driest sand dunes of Gobi.

It's described as a scarlet red worm, which gives it the appearance of a cow intestine, and can be between 60 centimetre and 1,50 metre (23,62 inches – 4,92 feet) long, and as thick as a forearm. It's difficult to distinguish between its head and its tail because it has no visible eyes or mouth. Some also describe it with dark spots on the body and spines on each end. We can suppose this worm is part of polychaetes, particularly eunice aphroditois, a omnivorous aquatic predatory worm.

Local Mongolians tell all sorts of stories about the olgoi khorkhoi. For example, the worm is said to be able to spit sulphuric acid, whose a single drop could make any metallic object rusty and could kill a human. It's also said to be able to kill at a distance away thanks to electric discharges.

Some others say that the worm is so venimous that the lower touch entails immediate death.

This mythic worm is supposed to live underground, hibernating most of the year and waking only in June and July. It can be seen on the surface on the rainy days when the soil is wet. It's said to prefer the rare parasite plants that grow in the Gobi, such as goyo, a toxic plant that tastes of banana and celery.

Although the inhabitants of Gobi have been telling stories about the worm for centuries, it's only in 1926 that Occident heard about it thanks to the book On the trail of Ancient Man by Roy Chapman Andrews. In this book, the American palaeontologist says how doubtful he is about the existence of this worm, even though he heard several stories about it: “none of the Mongolians I've met have seen the creature, but all of them wholeheartedly believe in it and describe it with great precision”.