The Sponge of Mystery is an alter-ego of SpongeBob. He only appears in the episode "Mermaid Man and Barnacle Boy II."


He resembles SpongeBob wearing underwear, a black colored mask, and a pair of dark green gloves.

Role in episode

SpongeBob guises under this alter-ego while on afternoon patrol with Mermaid Man and Barnacle Boy.

Later in the episode, while Mermaid Man and Barnacle Boy are trapped inside the Dirty Bubble, the Sponge of Mystery asks for his autograph and ends up popping him with his pencil in the process.