WHAT IS THIS??

It is a small solid thing. I always bring this when i go out from my house. Actually it is not really important because the function is not very useful. I think it is just for a fashion only. We can attach it to other things that more useful than this. It has a lot of different shape and color. And usually it is kind of a miniature of something. It costs cheap but if you buy the high quality it can be quite expensive. What is this??