Green Star Polyps not opening?

[InvertsBestVerts]

My GSP has been acting unusual for the last two days. Only one or two stalks are trying to open, with the rest staying completely closed. This is the first time they've acted strangely, and every other coral in the tank is still doing great. The only thing I've noticed are these hair algae like growths on the frag plug, but it looks way too thick for hair algae and I'm worried about damaging the coral if I try to remove it. I'd at least like to identify it first.

Does anyone have any suggestions?

 

[Copingwithpods]

Not saying it is, but a few months ago I got a gsp with those exact filiments growing out of it and it turned out to be bryopsis. I'd remove the frag pull as many as you can off and do an h2o2 dip to kill off the rest.