Zoa colony is not looking good

[lorenz0]

1 of my zoa colonies is not looking the greatest and i need some advice. I looked all over but i need some help since i couldn't figure it out.

They are all extending but the heads are shriveled up and the mouths have some black stuff coming out of it. all my other colonies look great, just this specific one.

also on a 5 star polyp the part that never attached to the rock looks like they have passed away and there are these white warm looking things on it they haven't moved. i am just going to cut it off since the rest all is all good condition but wouldn't mind knowing what it was