if it is white stringy stuff protruding from out of the corals body/ skin. it is more than likely acontia, all corals have em it is a defensive tactic sticrtly for attacking other corals or something that is irritating it. like the polyps are for feeding acontia are for destruction and will not hurt the coral but will indeed kill others. look it up on youtube, most easliy seen on anemones. i cant see clear enough on your photos but look it up