I acquired this from a friend... Not sure what is on it... Marker maybe... Old dirt of some kind... Unsure... Just posting for fun and to see if any real value and if I should put it in a protector of sorts... ???
It's almost twenty cents worth of copper. Some people collect them, but not with big stains like that. It would probably make a good paperweight as long as your breezes aren't too strong. It might also be useful for propping up an uneven table leg.
These are quite common at some coin show booths with any of a number of decorative designs. I tend to pick them up for grandkids stockings. They are fun but no real intrinsic value there.