Mermaid Man and Barnacle Boy's time machine is a machine that belongs to Mermaid Man and Barnacle Boy. It appears in the episode "Back to the Past," the short "Lessons Learned," and the online game A Mission Through Time.
The time machine is a large light blue machine with a large, yellow sign reading "Time Travel" in large magenta letters. Out of the top on both sides, there are red coils with light bulbs at the end. The words "Date" and "Location" are side-by-side at the top of the machine. Many multi-colored buttons that do nothing are seen at the lower end of the time machine, with a small radiator fan above.
The machine is located in a brown box.
Role in series
Mermaid Man and Barnacle Boy show SpongeBob and Patrick the time machine inside the Locker of Memories. Patrick stupidly puts a quarter inside a coin slot and claims that he lost his quarter, which sends SpongeBob, Mermaid Man, Barnacle Boy, and Patrick himself into the past.
SpongeBob and Patrick go back to the present without Mermaid Man and Barnacle Boy, where they find that Man Ray has established a new city. After freeing Mermaid Man and Barnacle Boy, they go back in time yet again to stop Patrick from eating the tartar sauce.
At the end of the episode, a lot of time machines start appearing, with time duplicates of SpongeBob, Patrick, Man Ray, Mermaid Man, and Barnacle Boy. This confuses the real Man Ray so much that he is captured. The episode ends with more and more time duplicates of SpongeBob and Patrick arriving.
SpongeBob and Patrick use it to travel back to the past and help their young selves become wiser.