Sea lillies on live rock?

[cathbad]

Anyone have an ID for these. They resemble miniature sea lillies, but they are only a few millimeters tall. I have others photos but this is the best of the closest.

 

[tableforglasses]

it looks like some sort of feather duster, but it is kind of difficult to tell from that picture. Does it retract if something gets near it?

 

[cathbad]

The only movement is at times a slight tilt of the "head" and less frequently the tenticles may fold together like an umbrella folded backwards. There is also no tube and their height does not change. Here is another photo for comparison. These are the best the camare (G2) will do without an addition macro lens, as there are only 2-3 mm tall.

 

[justinx]

Hydroids. Try and scrub em out with a toothbrush if you can. They multiply as quickly as aptaisa, and they are a real nusiance to corals.
HTH
Justin

 

[cathbad]

Thanks for the ID. Knowing what to look for really helps in identifying organisms better (I found a species ID and information on its natural history). Thanks again.