The copper plating was breached and the zinc core is corroding. Commonly known as zinc rot. The process is similar to rust forming on a car when the paint is scratched. In time, the cent will corrode to nothing so spend it soon As others have said, this isn't an error (unless you consider the mint choosing this composition for a coin an error ).
If a coin could talk eh?! It has a interesting obverse but I don’t think most of these aficionados can appreciate a damaged coin no matter the degree of coolness it has. My favourite damaged coin, which I hold in the same regard as my 1982 Silver Proof Regina Dollar seen as my profile pic is a 1935 Canadian Nickel pictured below.
The point wasn’t, if anyone could read, “is this an error coin and how much is it worth”. My impression was that the OP thought it neat and I agree... what forum did they post this in anyways? Errors? How much it’s worth? No they did not!
I'm a reasonably accomplished reader, and that's not how I interpreted the OP's post. I could be wrong, but I don't think anybody else did either.
Ok, it’s NOT an error. But it IS a neat looking coin in its own way. I especially liked the split T. Beauty is in the eye of the beholder. Otherwise I’d never have gotten married...