Music Boxes

When I was a kid my cousin had the coolest music box. I loved to play it. I can't remember now exactly how it worked, it had round metal plates, (like a record) and I think you could change the plate and play a different tune. The plate had little spikes sticking out in a random pattern and there was something that would hit those spikes and that made the music. I think we must have turned a crank to make it work. A few years back, my sister gave me a little hand crank music box built on the same principle, only the metal plate is round and it plays only one tune. It's a fun reminder of my childhood and my cousin's music box!