The Mongolian Death Worm may actually be a glorified snake. In fact, pretty probably. But peopel continue to believe an actual monster exists. In fact...
In 1990 and 1992, Ivan Mackerle led small groups of companions into the Gobi Desert to search for the worm. Inspired by Frank Herbert's novel Dune, in which giant fictional sandworms could be brought to the surface by rhythmic thumping, Mackerle constructed a motor-driven "thumper" and even used small explosions to try to find it.
Also, it is shaped like a sausage and therefore the legend might have started when someone found some very hot pepperoni in the middle of the desert. See also:
The Mongolian Death Worm: Original Theories