He is a huge sea snail with two tusks, an elephant/mammoth-like trunk, a purple shell with white dots, brown fur, and a unibrow.
Role in episode
At the Bikini Bottom Museum of Everything, SpongeBob and Patrick spot an extinct woolly mollusk on display which SpongeBob models into his pet snail Gary before morphing him back to normal. Since SpongeBob and Patrick have been promoted to security guards, they now have the right to touch anything on display, so SpongeBob climbs on top of the mollusk and creates an angel in his fur. Patrick angrily slams its buttons in a desperate attempt to get him to do more than just show his glowing eyes; the mollusk eventually comes to life after several continuous attempts.
It sucks SpongeBob and Patrick through its trunk and blows them out. The two are sent crashing into one of the skeletons and they land in a different section of the museum.
At the end of the episode, the mollusk reappears when SpongeBob spots it again. It comes to life again after Patrick kicks its shell and it lets out a loud mighty roar. It starts moving, but slower than before, which causes SpongeBob to continuously press its button until he and Patrick decide to get off of it and check up on Squidward.