Oh wow, that thing looks REALLY sick, being white. As much as I would like to give a positive reply, I honestly don't see that one making a recovery. Give it LOTS of light and LOTS of food and there may be a chance, but I suspect it may be too far gone. Seeing the Cyano on your rocks behind the anemone also tells me you have some things wrong with your water.. some parameters are off and probably not nearly enough flow if I had to guess.