I know “perpetual” is over egging it, so don't shoot me down. However, this is a fascinating example of how long a well balanced object can oscillate.
I've always been fascinated by those instances where simple objects can oscillate for ages with no external input of energy. I've seen it with a bunch of keys; where one is in the lock and others are hanging from the ring. The bunch oscillates for ages, rather than being damped quickly, as one would expect.In this case, I was making the morning tea and was attracted by the tiny ringing of one spoon on the other. If you listen closely, you can hear it, and you can see the left hand spoon is oscillating in sympathy as it is excited by the larger spoon. Actually it's two spoons on one ring.Apologies for the clock in the background.