Sometimes the pods are eating the dying or distressed tissue/slime/detritius...not actually a healthy animal. I've found that excess food/detritius sometimes accumulates on the connective tissue beneath the polyps and can cause either a fungus or, I've read, a bacterial infection as the food breaks down. It's always a good idea to blast the bases of your corals with a turkey baster several times a week. This will cause the detritius/excess food to be swept up into the water column and out of the tank. Also, a Lugol's or TMPCC dip can help halt the problem if the coral hasn't been damaged too severely.