F.U.N.

SpongeBob SquarePants is an extremely energetic and optimistic sea sponge (although his appearance more closely resembles a kitchen sponge) who lives in a pineapple under the sea with his pet snail Gary, who meows like a cat. Although Gary only speaks in a few episodes, the characters have shown an ability to understand him. Living two houses down from SpongeBob is his best friend Patrick Star, a dim-witted yet friendly starfish who lives under a rock. Living between the two is Squidward Tentacles, an arrogant and egotistical squid who lives in a moai and dislikes his neighbors (especially SpongeBob) for their child-like behavior. He enjoys playing the clarinet and painting self-portraits.

Another friend of SpongeBob is Sandy Cheeks, a red squirrel who speaks with a Texan accent and resides in an underwater dome in Bikini Bottom. She was sent there to do scientific research for her chimpanzee bosses. Sandy is an expert at karate. When not inside her tree-dome, she wears an astronaut-like suit because she cannot breathe in water. SpongeBob and Squidward's employer is former officer cadet for the Bikini Bottom Navy force and war veteran Eugene Krabs, a miserly crab obsessed with money and the founder of the Krusty Krab restaurant. Mr. Krabs’ archenemy is Sheldon Plankton, a small green copepod who owns a low-rank fast-food restaurant called the Chum Bucket across the street from the Krusty Krab. Plankton spends most of his time plotting to steal the recipe for Mr. Krabs's popular Krabby Patty burgers in order to obtain success, though all of his schemes usually end in failure.
(all get from wikipedia! =D)