Strange 2005 Proof Cent

I just received a few 2005 proof sets from the mint. One of the sets has a proof Lincoln Cent that kind of looks like a snow globe. There are thousands of little copper bubbles and nuggets all over the surface of the coin (more on the obverse than the reverse). It some spots, it looks like copper plated sand paper. Any ideas what caused this? Does this type of error have a name?

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KR
KR
0
Comments
The mint got a handle on the problem, but every now and then it will still show up.
Hope this helps.....
Pete
But FYI: in the same shipment I got the clad proof set, I also received 3 Silver Proof sets I'd ordered. Two out of the 3 Silver Proof Sets had coin damage, each having a very nasty scratch on one of the state quarters. I am sending those back.
KR