[0sprey]

I am well aware of what aiptasia looks like. (bergia nudibranches clear up that problem nicely, BTW, with no additional work on the part of the reef keeper). These have hard tubes and fine featherduster crowns, and they occasionally send a little puff of white stuff into the water column. I've never seen them trap solid bits of food; they aren't anemones of any variety. Definitely feather dusters. Normally I'd consider that a bonus; I have quite a bit of worm rock in my tank, but I'm worried about the safety of my stony colonies... Calfo's reef inverts book mentions that boring feather dusters can become pests, but doesn't offer any possibilities for dealing with them.