What happened to this nickel?

[Hopper39]

I assume it's PMD, but the pitted ring around the edge is raised from the obverse/reverse design (whereas if someone had applied a tool to it, the damage would be set into the coin), and the groove around the rim is just weird.

The weight is right.

Any insight would be appreciated.

 

[sagittarius98]

Definitely PMD, but I don't know what someone did to it.