Hey man I do away with that tube worm first off as they spit out a net of slime to catch/steal their food so my guess is maybe it's been irritating the flesh of the coral by doing this either scrap it off or super clue the opening!
Aha!!! Definitely not the tube worm, I got plenty of those suckers and their little web don't bother any of my chalices, except to steal food every now and then. Plus I do cut them off whenever I see them. But what you said reminded me that last week I had accidently hit the orange immolation with my pipette while feeding (it was in an awkward spot). I didn't think anything of it until you mentioned the tube worm. This may very well be what irritated the skin and caused it to get a little damaged and white. If that's the case, I'm actually very happy and relieved, since the idiot mistake won't happen again. Thanks so much for posting that or else I would have been stressed and depressed while trying to figure it out. If that's the case then no worries, I'll have it back to health in no time. Sorry for the screw up guys. I didn't think that a small jab from a pipette would stress it that bad but this being one of our most sensitive pieces, I now believe that may be the case.