Chinese container

I bought this in Shanghai in 1998 at a market. I have no idea what it is used for or what it's made of. It reminds me of a chinese ding or censer made of inkstone. There are 2 circular shapes in the container I thought might have been some sort of drainage but they don't go thru to the bottom. The container is heavy and measures 9.25 W x 5.75 D x 4.25 H. On the bottom there are 2 dragons and 4 characters. I'm trying to figure out what it is used for, so if anyone knows, I would love find out.