After watching this video it seemed to me it's swinging higher and higher?
Maybe you've all seen this and it's nothing new, but i post it anyway, seems interesting :)
http://www.youtube.com/watch?v=4VJ4sdHgcgM
Those kinds of toys usually have a coil and battery to give them energy.
"The Mini-Jupiter is a Kinetic Sculpture. Turn the sculpture on and watch it twist and turn. Use it as an Executive Desktop Toy or a conversation piece. Requires 1 9V battery, not included."
Just checked out what it's made of, and you're right. Mistery solved :D
PS: somebody with the name ken_nyus killed me on Battlefield 2 today :D