Feather duster looking thing on my rock ? I.d plz

[Guss]

Hello all I have this feather duster looking thing on my rock I just saw it. And on the side of my Duncan. Before I thought a new Duncan is growing from the side. But 2 day I saw similar looking thing on the rock and yesterday I saw one btw one of my zoa.i have pic I'll post. Is it same thing that's btw my zoa or diffrent .I have 2 on my rock and one or two also on the side of my Duncan.
And the ine on the zoa.

 

[ReefBridge]

I think they’re just hitchhiking fan worms. I have some that aren’t a big deal.

 

[ReeferWarrant]

Feather duster worm of some sort