Interesting 1865 3 Cent Error

This is an interesting coin. We have a nice dropped letter on the obverse. But what's that going on on the reverse? Hmmm.... We have some opinions from CONECA, the coin is there now, but I'm curious what everyone else has to say. Struck through metal? Maybe. There is definitely seems to be something extra there, you can see that the denticles are not where they're supposed to be. Click either photo to enlarge. Your thoughts?

We're real curious to see what this one goes for when we get it back.