Cave dwellers

The Cave Dwellers are strange, orange-brown creatures that are seen in the episode Chum Caverns.

Looks

The Cave Dwellers are strange-looking creatures that appear to have a great fear of cracking whips. Their skin is orangey with brown hair. They always make screeching noises when they talk. Their teeth look like walrus tusks. The Cave Dwellers have light green lips.

Discovery and Enslavement by Plankton

In the episode, Chum Caverns, Plankton and Karen discovered them as they attempted to dig under to the Krusty Krab, they fell into a massive, beautiful, natural cavern, populated by these beings. Plankton then enslaved these beings, and made them work his new restaurant, Chum Caverns, based on the principle that they would be so enchanted by the sencery they wouldn't mind the horrible food. Eventually, when everyone was trapped in the underground Krusty Krab, Mr. Krabs hired one of these beings, along with Plankton, to run the cashier. It is possible that these creatures are known in Bikini Bottom, at least to Plankton, considering he said,"cave dwellers!' when he saw them, as if he knew what or who these things were.