The Time Machine belongs to Mermaid Man and Barnacle Boy. It just appears in the episode Back to the Past. Patrick, who is quite stupid, puts a quarter inside a coin slot and claims he lost his quarter, which sends SpongeBob, Mermaid Man, Barnacle Boy, and Patrick himself, into the past. It is seen again, where SpongeBob and Patrick use it to go into the past a second time. At the end of the episode, it is seen that a lot of the time machines go into the past. According to Barnacle Boy, going through time is so dangerous, he and Mermaid Man choose to leave it alone.
- On the sign it says Time Travel.
- The Time Machine can be found in the Locker of Memories.
- On two signs, it says Date and Location.
- There are buttons everywhere, on two of them, it says Start and Back.
- The time machine is a possible parody of the TARDIS, a rectangular time machine from the long-running TV series, Doctor Who.