Pete

Pete is a pet rock that first appears in the episode "Sentimental Sponge."

Description
Pete is a bluish-black rock with white googly eyes and a drawn-on mouth.

"Sentimental Sponge"
He is given to by. SpongeBob plans on throwing it away until Patrick teaches him about the sentimental value of it, then the former decides to keep it along with most of the other stuff he was going to throw away.

"Lost and Found"
At some point, SpongeBob lost Pete and it ended up in the Krusty Krab lost and found.

Sponge Star Patrick Pants
He can be seen in Patrick Star's house.

Beachy Keen!
He can be seen in the Jellyfish Fields level.

Trivia

 * Pete the Rock is similar to one of Patrick's masterpieces in the episode "The Googly Artiste," which is also a episode.