to me the edges look raised up some i tried peeling back with finger nail thinking maybe glue but feels solid
If its ancient glue of course its not going to come off like it was put on a few minutes ago,it hardens overtime on the copper.
If you notice that the outside edges on either side of the anomaly (which I think is adhesive residue from very old clear tape) is very straight. As it gets closer to the device in the center it 'vanishes' as if there was an air gap where the tape could not contact the coin until it made contact again on top of the device. An acetone bath may help this one to soften the stuff on it.
Probably a very old glue or adhesive. You can try to soak it in acetone and I don’t mean fingernail polish.
Ah......the memories. When I was a little kid in the mid 70's, my great grandma used to send me birthday cards every year with a coin always taped onto the inside of the card. Every year after I was 5 the coins got bigger. First 2/3 years it was a penny, then a nickel and then a dime, and I remember once two dimes, and then the big one....a quarter, I was about 8 at that time. If I still had one of those cards with the coin still taped in it today, I'm sure the penny would look a lot like this one the op posted. Those were some good times. I doubt anyone does this anymore. Perhaps remnants of those who grew up in the years of the great depression I suppose.
24 to 48 hour soak in 100% acetone and then use a cotton tip to lightly rub the areas and I will probably come off, but in reality, it's just a cent, so is it worth the acetone and time? Only you can answer that question.
