Or would it be a fin? What do you call the "arms" of a turtle/tortoise? Either way, this vid is pretty neat!
http://www.pawnation.com/2010/06/24/sweet-video-of-the-good-samari-tortoise/?icid=main|main|dl8|link5|http%3A%2F%2Fwww.pawnation.com%2F2010%2F06%2F24%2Fsweet-video-of-the-good-samari-tortoise%2F