feather dusters?

[cordodor]

are feather dusters fan worms? these don't suck back into any "worm tubes"

these have lived in my tank since i bought the rock 1.5 yrs ago, but they haven't really flourished till i just replaced my flourescents w/ new PC's.

 

[Fluff]

Looks like colonial hydroids. Either myrionema or athecate. These are stinging animals that can cause havoc with corals or clams in the tank if left unchecked. Control them by lowering the nutrients in your tank. Don't overfeed, keep up on water changes, etc. Otherwise, manual removal will be necessary to help rid the tank of them. Wear gloves while messing with them or around them and wash well afterwards. Use a small brush (tooth, nail) to brush them from the rock while using a piece of airline to syphon them out of the tank as you go. HTH

 

[cordodor]

good to know, Fluff. Thanks for the info