Small white hairs - ID

[D3DPrintedThingz]

First 3 pics are from my tank. Started noticing 1 or 2 very small white hairs growing out of my rock. They are spreading now in the tank so I need to ID them.

possibly baby feather dusters?

 

[ScubaFish802]

spirorbid worms maybe? I see it now, looks like some sort of sponge possibly

 

[Dooly]

If it looks like a brittle white beard is growing, bryozoan? If you touch and they retract, possible digitate hydroid?

 

[D3DPrintedThingz]

Do sponges multiply quickly? The digit are hydroid seems too long, these are only about 1/4” in length. It almost looks like a flower bloom