1953 D Nickel - Weird D Mint Mark?

Can't quite make out what's happening, given the posted pic. Please post a sharp, closer-in image of the mint mark. It's likely damage from many years of circulation,. A better photo will help. Thanks.

@hum, there are two main reasons why a D mintmark will be filled in like yours. Either the post on the die that forms this central space was broken when your coin was struck or else wear and mechanical damage have "smeared" the metal of the letter D around enough that the middle part is covered up. With the amount of circulation wear on this coin, it may not be possible to tell. With that said, having a so-called broken post die chip doesn't affect the value of the coin anyways, so it would be a spender unless you want to keep it for being interesting.

I'll go with circulation flattening

Pretty much so - just damage - no other pics neede!