I know it's a long shot but what if?? First is before it was cleaned and then after. Its not real heavy like a metal. It is covered in a rusty haze but can be polished very easyly. Seems rather sturdy. But because it lacks the basic metal properties? What does that leave ? Or if metal was real dirty along long time ago (long time ago) less pure than say the bronze. Than the metal could rust away leaving a sorta fossilized coin of sorts? That's the best description and idea I got.