Odd, no? Technically, it's not a bouncy ball. What it is is the ball from my old mouse. When it died on me, I took it apart, and just couldn't bear to part with the cool little rolly ball inside it. It's a heavy little sucker too. But the truly odd part is that while its outsides are rubber (I don't know if it's solid all the way through, or filled with heavy things, or what), it has no bounce whatsoever on hard surfaces. It completely absorbs motion and force. You throw it at the floor, and it maybe gives a quarter inch dribble and stops. However, I call it a reverse bouncy ball because it bounces on carpet. Normally bouncy balls just don't work well on carpet. They tend to just stop. This mouse ball though, it bounces on carpet. Maybe only half the original height of the drop, but still, it's pretty impressive. I'm guessing it has something to do with the weight of the thing, but regardless, it's pretty darn cool.