What are these?

[keithadaniels]

I'm very new to reef keeping. My 29g biocube as been up and running for a little more than a month.

Can anyone ID the long white feathery things in this pic? They are a few in different spots in the tank. At first I thought they were poop from my blenny (my only fish so far). But on closer examination they are clearly something alive because they disappear (retract) and reappear.

I so hope that they are harmless since I've already dealt with aiptasia and bristle worms.

Thanks.

 

[33mm33]

looks like some sort of a hydroid

 

[tektite]

Digitate hydroid

 

[Sugar Magnolia]

Digitate hydroid

Yes, this.