Fabric port of the cave dweller mod by Gargin.
All credits go to him for the initial release.
From his description:
"The Cave Dweller is a complex entity that has multiple different animations, sounds, and behaviors.
As you explore caves, you will be stalked by this monster. As he gets closer, the cave sounds will get more intense."
Has a lot of configuration options.
The code used for the port is based on SiverDx work to port the mod to other forge versions.
(https://github.com/SiverDX/cave_dweller)
Requires
https://www.curseforge.com/minecraft/mc-mods/owo-lib
and
https://www.curseforge.com/minecraft/mc-mods/geckolib