u/Feeling-Policy-8994

Saw this at the register, no clue either way what’s wrong with this dime? It looks to be on the bottom side of the tails. I included a picture of the heads.

I noticed this at a cash register but my dime seems to have an extra ridge in the bottom part of the coin. I immediately recognized this as I’ve been for as long as I recall seen this type of coin since childhood. Never seen an additional ridge it seems to be it’s already difficult to make it what exactly it is. Is this a fake coin? I included a photo of a closeup with a knife to amplify the ridge.