live rock identification

[Daniel Morris]

Hi All,
I have had my 50gal Marine tank for a whole 1 week now (no fish yet)
the Live rock seems to be responding well with coralline algae here and there and other bits and pieces. One of the things growing in a couple of different areas are these small red threads with 3 or 4 tiny arms at the top (see attached pic) any suggestions what these are

Cheers

[Daniel Morris]

no takers :)
I was just wondering if it will grow to be friend or foe

[hersheyb]

It's really hard to tell from the picture, does it retract?

[Daniel Morris]

If you click on the pic its quite visible. It doesn't seem to do anything just moves with the water. Guess I will have to wait until it gets bigger :)