Tube Worms Gone Fishing - What Are These?

[reefnstuff]

I finally got a good macro shot of the small tubes in one of my tanks but can't figure out what these are.

They move in and out a little, seem to push out a string of mucus or similar, then reel it back in like they are fishing, which makes me think they are serious about catching fish.

Any ideas what these are?

 

[Betta132]

Vermatid snails. They are indeed fishing with mucus, but they're after small particulates... Not fish. I suppose they might be a problem in a fry-raising tank but they're harmless to all non-plankton things. You can leave them alone... Won't hurt anything.
Never quite figured out why these snails stay in one place, but oh well.

 

[reefnstuff]

Thank you. I found you are right about those being vermatid snails, but seems just this week a scientific study was confirmed that found vermatid snails impede coral growth and discourage algae eating fish.

Advanced Aquarist has a nice pic and some good info, but in a nutshell, your tip helped me realize these need to go.

Thank you Betta132

 

[Betta132]

Really? They can mess with stuff? Well, I'll remember that.
Ah, I know... The mucus nets. If the nets got on things, I suppose they could irritate corals and taste nasty to fish. Makes sense.
I never had the big kind, but I had the eeny-weeny kind that never really look like anything more than specks with tiny chimneys.
You're welcome!