My Biota Mountain Dew Toadstool has developed white spots and yellow patches on the foot. It is easy to scrape off the yellow patches with a toothpick, and underneath the flesh is white, but it leaves a whole. I took pictures under different lights. Is this a disease or fungus or something else? Any help is appreciated. Polyp extension is fine, as are other corals in the tank (incl. LPS and SPS).