Help with identification of unknown coin

[Help with identification of unknown coin]

14 hours ago, Rob said:

Pictures are too dark to be much use, but it looks like IOAN CASI and the date is 1661 in which case it is probably Johann Casimir of Thorn in Poland. I can't match anything, but there again I can't see much in the picture. Whether it is real or not I can't say. Size?

Sorry for the lighting, it has a diameter of 16mm.

[Help with identification of unknown coin]

Hello, I've had this coin for a while but am unsure of what it actually is. Hopefully on eof you'll be able to help me identify this coin, it seems quite mysterious to me.

Thank you.