'Who Is Mermaid Girl?' Part 1 of 2. Sandy and SpongeBob set out to discover the identity of the mysterious Mermaid Girl - a plucky heroine who has aided Mermaid Man and Barnacle Boy for years. But first they have to confront the deadly, non-dexterous Hammerhands Shark! Also, Mr. Krabs tricks Patrick and SpongeBob into cutting his mother's terrifying lawn in 'Mama Trauma'. Plus: Meet SpongeBob's new imaginary friend - courtesy of your real friend James Kochalka (Quit Your Job) - and check out Patrick's horrifying new look, as designed by David DeGrand (Garfield, Uncle Grampa).