 Another close friend of SpongeBob is Sandy Cheeks , a squirrel from Texas . She is a scientist and an expert in karate . She lives in an underwater tree dome ( a tree Sandy brought with her that is entrapped in a clear glass dome locked by a tight , hand @-@ turned seal ) . When outside of her dwelling , she wears an astronaut @-@ like suit because she cannot breathe underwater . Mr. Krabs , a miserly crab obsessed with money , is the owner of the Krusty Krab restaurant and SpongeBob 's boss . His rival , Plankton , is a small green copepod who owns a low @-@ rank fast @-@ food restaurant called the Chum Bucket , located across the street from the Krusty Krab . Plankton spends most of his time planning to steal the secret recipe for Mr. Krabs ' popular Krabby Patty burgers , so as to gain the upper hand and put the Krusty Krab out of business . 
