Small Black Clay Vase shaped like a breast

This is an exceptionally thin, light vessel that is shaped like a woman's breast with the nipple on the other side. I don't see any markings on the bottom but have uploaded a picture of it in case that means something to anyone else. I have not seen others like it and don't know where it is from. Mexico maybe? It is pretty small -- about 6 inches or so.

Thanks all.