The coin I thought was hammered turns out to be US, and check out the other US .... this is weird... the date stars and writing are all indented as opposed to be raised... very weird!!!
That’s cool looking. Glad you got a Id.
My guess would be when the coin was in use it had some sort of dirt on it. Than it got some ware on the high parts that removed this (dirt) from the high spots. When it was lost the (dirt that was on it) protected the low parts. Corroding the high parts but not the low parts.