Dr. Doom (MATA)

Dr. Doom is Tahu's pet dermis turtle.

Season 1
The turtle first appeared when Gali had set up a protest to save the dermis turtles and was used as an example. However, when Tahu presented him, he was worn like a hat ("What the Dermis Turtle?"). It's later revealed that Tahu kept him and named him "Dr. Doom" and uses him to interrogate Lewa about the previous events ("Chat-Talk").

Trivia

 * Initially the turtle was never meant to appear again, however during the writing of Chat-Talk, the episode's writer felt it would make sense to bring it back, considering the episode's plot revolves around events from What the Dermis Turtle?.