Hi Welcome to ct! Imho, it looks like someone cut the rim off then hammered the rim out with a chisel. Then acid dipped. It looks remarkably smaller than an original nickel.
It's probably acid as that is one of the only things that will eat the metal away. While surprising, many of the details will still remain intact. If it was rolled thin, it would still be the same size as a regular nickel, almost as thick, and just a little lighter. This coin is much lighter and much smaller in diameter.
I suspect it was not a normal school chem lab acid, even after any possible metalwork. It looks like something of the nature of fuming nitric acid ( High % above 50%), or very long exposure with refreshed acids. Tough metal, IMO, Not for an amateur, even if they still have their fingers and vision. Jim
What's it weigh? The damage seems too uniform on the rim, and the high relief. Foreign planchet??? Weak punch too thin of a planchet? Just pitching out some hunches. I'm with @desertgem a extremely volatile PMD attempt for no gain...
