"Why do they need wheels if they can roll on thin air above several black holes without being sucked into any of them?" We will never know. :) That reminds me of Twilight Princess and I think Windwaker, where there are these moving floor black hole things that can grab you if you get to close. If they are black holes, why don't they just suck you in anyway? Why do they have arms? I have no idea, but I like them.