The Cave monster is a monster who first made a cameo appearance in the episode "Your Shoe's Untied."
The monster is lime green, with light green lips. He has numerous tentacles that allow him to move. He has a large amount of eyes in one area, with lids all differing in colors. He has one large blowhole on the top of his head, of which he shot SpongeBob out of. The cave he was residing in was relatively small and an obvious problem for him, which can be noted by the stretch marks on the side of his body, caused by attempting to squeeze through the opening. He most likely still resides in the cave.
He ate SpongeBob after he asked him if he knew how to tie his shoes. In the monster's mouth, SpongeBob asked a human skeleton with fishing gear if he knew how to tie his shoes. Afterwards, the monster shot him out of a blowhole.