Ok, this has been absolutely killing me since yesterday. I am talking about that model where you have a stationary ring, and inside that, is a slightly smaller ring that spins around, and inside that is another ring that spins around, and so on. What is the thing's name? The only picture I can find of something that resembels what I'm talking about is the alien machine thing in Carl Sagan's "Contact":
For some reason, I am being murdered in my head because I can't figure this out. It's kinda hard to get good results on Google when your only description is "ring with rings spinning inside". HELP ME PLEASE!
