Vurms

A life-form dwelling in Dwarf mines, originally found in the deep caves in the mountains around Llamedos. Swarming, or slithering, by the hundred, packs of Vurms generate a low but steady luminescence which enables the adapted eyes of Dwarfs to see their way in the deeper mines.

They are adapted to seldom require feeding, but are carnivorous creatures living on carrion. They are attracted to blood and corpses and will smell dead animals - or dwarfs - from a long distance. After a feed, they will shine very much brighter. Almost anything is food to a vurm, who live so deep underground that even a breath is food, blood is food, and anything that was once alive, no matter how mangled it is, is food. Vurms are shown to be so attracted to blood that they would rather die then give up their feast, as shown in Thud!.

Carrot Ironfoundersson is all too aware of this when investigating a murder in the Dwarf community in Ankh-Morpork, during the events in Thud!.