"There's just six of us overall. Me, my brothers, my father and a friend of ours named Leatherhead. At least that's all as far as I know." Donatello rubbed his head. "Only me and my brothers are actually turtles. Master Splinter is a rat and Leatherhead is a crocodile. But we were all mutated by the same thing, and we all live in the sewer near one another."