White hair, maybe spionid?

[Clutchiee]

This coral has not grown over this area filled with these tiny white hairs. It is very thin and small so idk what it is.

 

[ISpeakForTheSeas]

Not spionids (you'd see two tiny "hairs" sticking out of little holes for those). These may be tiny feather dusters of some kind, or they may be something else entirely. Unfortunately, I'm not sure in this case.

 

[EeyoreIsMySpiritAnimal]

Not spionids (you'd see two tiny "hairs" sticking out of little holes for those). These may be tiny feather dusters of some kind, or they may be something else entirely. Unfortunately, I'm not sure in this case.

Digitate hydroids?

 

[ISpeakForTheSeas]

Digitate hydroids?

Possibly - I can't see any polyps branching off in the pic, but that doesn't mean they're not there.

 

[Rick's Reviews]

Could you scrubb it off out of your aquarium, my GSP gets this all the time, it looks like salt on it, hydrogen peroxide works in small amounts

 

[vetteguy53081]

Tube worms and can be scrubbed off placing coral in a container or bowl of tank water with a firm toothbrush or scrape them off with a paring knife