Someone could have heated it up at the top and caused the outer coating to bubble, or even solder it to something causing those little bubbles, and heat transfer to obverse.
Thank you for the reply! One side has less/missing copper. The blobs are part of the copper plating. The coin is smaller than the other pennies and has an otherwise decent image, (Not melted looking or burnt) Any other possibilities maybe?
It could be a multitude of things. I know I’ve really put some heat on them before, and it turned the opposite side the same color. The plating on the one side that’s either bubbled up from heat, or it’s a blob of something someone may have tried to solder or braze it to something.
Just another rotting Zincoln. Despite the inference from your post title, this is not an error. The copper plated zinc cent is the victim of its own design.
Very thin copper plating over very reactive zinc. Any compromise of the copper plating, however small, will lead to extreme degradation of the coin.
I see no evidence of of heat, but I do see evidence of adverse environmental effects. And some foreign material.