That's too bad fishheads. Do you have a place you could put it in a separate container to monitor it? If there is anything at all left of it when it is done, it will come back, but you don't want it to pollute your tank in the meantime. What have you tried to save it? I would dip it in an iodine dip, then put what is left of in a container on fresh saltwater, matching parameters as much as possible and keeping the water aerated. You will likely need to do a few major WCs on the container to keep it from being polluted as well before it is done doing its thing. If it isn't melting away too bad, I have also done just the dip, placed it in fresh saltwater just long enough to rinse the loose stuff off of it, then put back what is left of it into the tank (depending on size of the tank and what else is in the tank).
Good karma headed your way...