Holashner "The Hunger Below"

Holashner “The Hunger Below” is one of the few remaining Elder Evils from The Far Realm that remain on this plane. It is an enormous entity reminiscent of a centipede/worm.
Driven by its unending hunger, it burrows through the deepest reaches of this world by devouring all dirt, stone, and minerals in its path. It leaves behind a tar-like substance called Black Bile which over time can be compressed and refined into Bile Stone which is similar to obsidian in appearance.