I bought quite a few unidentified coins from the German states recently, and this one was amongst them--the only one I have not been able to identify. Not much to go by though:


(The pictures are kind of blurry--my apologies for that.)
It is 20 millimetres in diameter, and I do not have something to properly weight it. But it is not heavy--a rather thin coin (does not seem to even be half a millimetre).
I have no idea where to start looking for this. Might not even be German. So... does anyone happen to recognize it or have any suggestions?
Thank you for your time!