Slash

Spike, aka Slash, is an ally of the Ninja Turtles. Formerly as the pet tortoise of Raphael, he was a turtle that was rescued by Raph after he found him in the Sewers. But after Raph supervised a canister of Mutagen that he confiscated and the canister broke, the turtle submerged into the ooze to mutate himself into a mutant tortoise.

Official Description
"I was Raphael’s pet until mutagen made me his equal! Raph’s my bud, but I had a bone to pick with the rest of the team—they’ve never treated Raph right! I planned to wipe out our dead weight…then Raph and I could form the ultimate Turtle team. However, now I'm right in the head. I've become the leader of the Mutanimals, and we're always ready to fight the Kraang!"'

- Slash