The name really describes it well....
But I'll describe it anyway, before modern villagers we had these. thought to have gone extinct over 10,000 years ago, we have recently discovered an underground cave village! they have been able to defend themselves using stone shovels enchanted with sharpness,knockback,and fire aspect! and they survive on mushroom stew and rotten flesh. They seem to enjoy mining for ores, and they seem to worship emeralds. Though they seem very primitive they are very good with redstone circuits, their redstone traps are near undetectable!