Came across this in my father in laws penny book. I have been reading different error types but I am not sure how this one even happens. (or if it was an after the fact thing). Not worried about the "whats it worth" aspect... unless its a lot... My daughter and I have been going through her grand parents (and great grand parents) collection to try and fill up her own book.. Lots of cool coins so far... this one has be stumped.
It looks like someone took a punch to it. Sorry, but it is just damaged. As a forth generation collector, I love that you are carrying on your family tradition of coin collecting though.
@LazloH I have seen these before. Someone punched out a small part of the Cent and turned it around. Attached it back somehow. Not a Mint Error.