Good morning. Are there any markings on the back side? A picture with something for size comparison might help.
I see this is your first posting, so welcome to the forum. I also see you've been a member for several months so you know their are some pretty sharp cookies on here so hopefully they'll come along soon with an I.d. for your find. Sorry but I'm clueless.
Interesting find... but I have no idea what it is. Good luck in ID'ing it. Look forward to more information from the smart guys on this forum. Thanks for posting.