[Somebody doesn't like Monticello] [1][But it's worth $0.0624439 as per today] [2]I was going through my change in the car today when I found this nickel and while the front is typical, it was the back that caught my eye—it looks partially melted. It's not been shot, that would have deformed the coin and this is still quite normally flat. I doubt it's an arc-welder as the front is still fine, and there don't appear to be any scorch marks along the back.
Perhaps acid?
Anyway, it's pretty cool looking.
[1] /boston/2007/01/06/nickelback.png