Sheldon J. Plankton is the main antagonist of the popular cartoon series SpongeBob SquarePants. He is an evil zooplankton and the business rival and personal archenemy of Mr. Krabs. Plankton owns his own restaurant called the Chum Bucket, less popular than the Krusty Krabs and has very few customers. Plankton's plans all revolve around stealing the elusive "Krabby Patty Secret Formula" so he can copy it and make the Chum Bucket more popular.