Sam is a large, overweight, and muscular sea star with coral pink skin. She is roughly twice the size of Patrick. She has black hair which she wears in a side ponytail that is fastened with a light lime green scrunchy. Her outfit consists of a violet-blue top with flowers that are the same color of her hair scrunchy, as well as a matching skirt. Sam has a very deep voice; similar to a caveman's (despite usual females having much higher voices). She often calls herself "Sister Sam." She can literally put on her mean face whenever she completely loses her temper by turning her head around. She becomes very aggressive and destructive and can end up destroying anything.
Sam is shown to be highly aggressive by her clarity. This can be true as she is easily angered by any person she does not recognize. However, she expresses a brotherly bond with her younger brother and defends him from the other neighbor SpongeBob when she mistook physical contact as aggression. In addition to her supportive behavior, her level of intelligence is relatively lower than Patrick's as she speaks incomplete language and has no regard for other people. She talks in third person. Sam is the only known sibling to Patrick.