Prehistoric Gary is a sea snail and the prehistoric version of Gary that only appears in the episode "Ugh". He was owned by SpongeGar.
Prehistoric Gary looked almost identical to the modern day Gary, but is larger. The only real differences are that Prehistoric Gary had light green spikes coming out from his shell like how a gigantspinosaurus has spines from it's back, had a Stegosaurus-like tail, and sported a thick unibrow that resembles Squilliam's.
He first appears when SpongeGar leaves and says, "Bunooga ready! Tabunga, Gary." Gary does not move. SpongeGar says more sternly, "Gary, tabunga!" Gary finally obeys. He knows Squog is very afraid of him due to his size. Prehistoric Gary leaves slime trails everywhere, which annoys Squog. His slime trails are commonly known as "tabunga" among the trio.
Prehistoric Gary also appears in Lights, Camera, Pants!, but was not a huge monster. Also, when the mouse rolls over him, captions are not seen.