Chumbot
The Chumbot only appears in the episode Enemy In-Law. Plankton uses it to destroy Bikini Bottom and steal the Krabby Patty Recipe from Mr. Krabs. When Plankton sees Betsy Krabs, he falls in love with her. The Robot is so tough that its fist can break a huge rock in small pieces. The Robot is seen again at the end of the episode.
Looks
He is silver, and has antennas (like Plankton). He is practically like Plankton, but a robot and is bigger.