Can Anyone Tell Me What This Is?

[mysonandi]

Shortly after curing 75lbs of Live Rock, I noticed several of these little guys on different rocks in my tank. Sorry for the picture not being too clear, but he is small and if I get too close he retracts back into the rock. They seem to be stationary other tan retracting.... anyone know what these are and if they are beneficial or not?
Thanks in advance for your time and Info!

 

[toan]

feather duster perhaps.. picture needs to be clearer though.

 

[crzyfshygy]

I agree

 

[mysonandi]

Assuming that is the case, can I expect an increase in size or will that depend on the type of dusters involved? The rock was supposed to be premium Fiji.

 

[alyssia]

I don't think they get much bigger than that.

 

[bonebrake]

Feather duster. It will likely remain that size.
:joy:

 

[fedukeford]

it kinda looks like a zoanathid. When it retracts does it turn into a little ball, or is it just totally gone?

 

[booduh]

My vote is for feather duster as well. Premium live rock should have small inverts, sponges, etc. on it. Usually the small feathers that I have only reach about the size of a dime, but they spread. They are also benificial, filter feeders that will remove excess wastes in the water.

 

[cymbal67]

feather duster. when you see one, you will see more.

 

[natureboy]

Definently a feather duster i have a few in my tank that look just like that. Dont get very big at all and havent spread very fast.