what is this

[aquanaut]

this strang things are poping out on my fish tank what is this?

 

[AUEagleinDC]

looks like small feather duster worms living in the rock....won't cause any problems and makes something neat to watch...take it easy...chris

 

[Anonymous]

It does indeed look a lot like a feather duster, but I'm pretty sure it's a sponge in the genus Leucilla. Check out the Hitchhiker's FAQ for more info:
http://www.reefs.org/hhfaq
They will proliferate like mad in your skimmer, powerheads, anywhere shaded and with high flow. HTH, Matt.

 

[fishfanatic2]

Yes, I too believe it is Lucilla, since I have them growing in my tank.

 

[Reefguide]

looks to me like a thread hearing with it's head stuck in the rock ! Sorry :?

Yeah, looks like feather duster...

 

[Anonymous]

Definitely a sponge; I always call them sycon sponges- not sure if thats correct or not.

 

[TrevorRobertson]

I would agree with the sponge theory, I have had a number of them grow (out of the rock) in my tank over time.