Hello, first time posting here... I've been back and forth between half a dozen possible errors with this one. I thought I knew a decent amount about various errors, but I've been confused about this particular coin for awhile now. Of course at first I thought someone had just sanded it down, but there aren't any typical 'sanding' marks on it? There's also the obvious indent, which appears to have a very faint date of some sort inside of it, along with what looks like a 'D' (I'm not sure how to get a picture with the necessary magnification to show that, sorry.) The reverse almost looks normal, except there seems to be some sort of image struck in the middle of it...however, I can't make out what it might be..? It's underweight at 4.77 grams and is thinner than a normal nickel. Thanks for any info and/or ideas!