I know that this is not a real mint mark..was looking for insight to what causes a raised feature like this ? Does not have any hole on reverse. Why would it be so close to a perfect circle with a raised rim ? Is it caused from the zinc inside after being struck ?
No zinc inside a bronze cent and it's too big for any mint mark. It's most likely something on the planchet when struck or welded on (for some unknown) reason after.
It looks like it could even be two semi-circles joined together. I don't see where the "O" goes under or over the second Number 5 in the date. I would guess this was done by someone for the novelty, or perhaps for practice to alter or add mint marks on other coins.
What I meant to say when I said caused from zinc..is Gas expansion or something to that effect...blow out ?
