looks like bristleworms to me. does it look like one of these (A)?
http://www.seaslugforum.net/images/030246comb.JPG
if so, bristles are no harm. they just eat detritus and stuff. like part of your CUC. just don't touch them because they sting. remove any that are over a foot long. very few actually eat corals like zoos, and all the stories ive heard of coral eating bristleworms involved a worm well over a foot lopng.