I just noticed this last night on one of my Millies, Non of the other SPS corals in the tank seem to be affected at all. I am going to be doing a water test here soon before the water change. Last time I saw this happen it was flat worms but I cant seem to see any on the corals.
DSC03586 by Titan-Uranus, on Flickr
DSC03586 by Titan-Uranus, on Flickr

