She is a pink colored worm with light yellow eyes and black pupils.
At first, she seems tame and docile, but from the way she acted, Mrs. Wormsley gets quite angry with Gary, making them fight each other. This is because she and Gary hate each other as they fight like cats and dogs as they are the underwater equivalents. Gary once again fights Mrs. Wormsley and wins the duel, abandoning her newborn litter and most likely leaving town.
Originally, SpongeBob called the worm Mr. Wormsley thinking she was a male. Soon, though, he discovered it was a girl when she gave birth. Mrs. Wormsley had five small babies, and they were sold at the end of the episode.
In the German version, she is called "Frau Würmlinger," which means "Miss Würmlinger."