Found this today at vacant city lot. It looked like a round stone when it was all dirty; it reacted to the pin pointer but it looked like some kind of nothing. When cleaning it up I discovered it had a nice monogram initial, H I think and could be pried apart. So it is a pendant of some kind. Inside there was a chain wrapped around an inner winder and there is a hole where the chain would come out. Guessing it was on a spring coil where the chain would come out and go back in. Never saw anything like this. I initially put it in the trash bag but then got it out and looked closer at it. Will take it to a jewler to see if the chain is gold. Probably not worth anything but it is interesting.