Green Button Polyps

[drrivas]

A week a go, I got the green button polyps.  They are doing good but I have noticed a white band of some kind around the "tube" of the coral.  I only see it on the polyps on the outer edge of the group and the ones that have it don't seem to be doing to well.  Is it a parasite of some kind or is it a sinthetic material?  

Thanks!!!

[LMTB731]

I have seen the exact same thing around my brown zooanthids as well.  As soon as it appeared my polyps started shrinking in size and never opening.  I had gone into the tank a few times and pulled off the "tube" with tweezers and it would come back the next day.  The damage has been done I think.  I saw a bristleworm coming out of the "tube" one time but not again since I pulled it off the last time.  Other than maybe being a home for a worm, I don't have a clue what that "tube" is!