Margaret[2] Claire Gretchen[3] SquarePants (née BubbleBottom[4]) is SpongeBob's mother and Harold's wife. Unlike SpongeBob, who is a squared-off tube sea sponge, Margaret and her husband are designed as round sea sponges. Although both SpongeBob and his parents are modeled after real-life species of sea sponges, it has not been explained why they are different kinds.

The decision to have SpongeBob's parents resemble round sea sponges was a reference to SpongeBob's original design.﻿