Dude, check THIS shit out. I'm sure there's some really touching story behind this about the love between a man and his tortoise or something, but all I'm seeing is an animal and a wheel.
But now that I think about it, why stop at one leg? Tortoises would be a lot more efficient and pet-worthy if you just replaced all those little land-fins with wheels. Little propeller on the back, maybe, like those Everglades boats? That would be much more economical.