feather duster?

[marty20]

I have no idea about feather dusters but these two showed up in my tank about a month ago and I was wondering if that was possible? They just appeared on the back side of my live rock and they retreat like a feather duster would if a fish swims by them. I realize the picture sucks but hopefully its good enough.

 

[paul87]

Yep. They are good. I gave a bunch that just pop up.

 

[marty20]

Thanks! Do you know if they will grow to get pretty large or will they stay kinda small?

 

[paul87]

Not really sure. I've seen some pretty big ones at the lfs. The biggest in my tank is about the size of a penny when its open. I'm sure there are different species of them.