Patrick's Pet Rocks
Patrick's Googly Pet Rock
Patrick's Googly Pet Rock appears in the episode "The Googly Artiste." Patrick made it with a lot of googly eyes and used glue to stick them on the rock. He sold them off as art.
Rocky is a rock, which Patrick mistook for a snail. Patrick entered Rocky in a snail race in the episode "The Great Snail Race," competing against SpongeBob's pet snail Gary and Squidward's pet, Snellie. The rock goes on to win the race at the end of the episode. Rocky appears to be the only pet rock that is 'alive'.
Pete is a rock with Googly eyes and a drawn mouth that was given to SpongeBob by Patrick in the episode "Sentimental Sponge." SpongeBob was going to throw it away until Patrick taught him about 'sentimental value'.
Squidward's Pet Rocks
SpongeBob's Pet Rocks
In the episode "The Googly Artiste," SpongeBob creates a Googly-eyed pet rock as a guide for Patrick to make one for himself.