(Excited, conspiratorially) While I have absolutely no evidence to support the idea, I can't help but think that Tank is a changeling. Think about it! He's clever, compassionate, surprisingly active and resourceful, he was apparently desperate to be Rainbow Dash's pet, and you know how constant and enthusiastic aunt Rainbow is about loving all of us! If that doesn't compel you, when was the last time you saw another tortoise who wasn't a selfish stick in the mud? I rest my case.