This is a case of the title being somewhat astray of the truth. The worms aren’t worms like we would recognize, but near microscopic nematodes—a kind of primitive round worm about ½ millimeter long. And they have no behavior that one might associate as being devilish. So, why the radical name? It seems these particular worms live at the furthest depth of the earth—some found a mile underground in a South African gold mine. They live in toxic environments at high temperatures—rather like living in hell. What makes these creatures especially interesting is how they have back-up genes to protect them from low oxygen and high levels of methane gas.