In the movie "Alien" by Ridley Scott, there's a Drinking Bird which, presumably, the crew activated when entering stasis, and which is still going after they emerge. However anyone who has had one of these birds will know that they don't last long at all. But it made me curios to know if there are better examples of perpetual motion style machines that could actually last years or maybe even decades in a spacecraft, given vacuum and micro-gravity?

The only one I can think of is a spinning sphere or disc suspended in a vacuum. Should last a very long time, but it's not very flashy or interesting. Any ideas?