I believe it's a "spinner": Spin it fast, and the images of the two wrestlers combine, to look like they're wrestling.
Spinners are usually mounted in a loop to make spinning it easier. I'm guessing the dints at 9 o'clock and 3 o'clock are what remains of the loop mount.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis