what are the small tubes on my rock

[ferrybongo13]

are these good or bad...small tube worms?

 

[MikeyZO]

looks like feather duster tubes.

 

[ecvernon]

i cant remember the name but its not a featherduster..it lets go some sort of like string web so that it can catch floating food then pulls it back in. i have them in m y tank also and the webs can be an irritant to corals. i have tried breaking them off but the grow back because the base is usually inside a crevice of a rock

 

[KathyC]

They are called Vermetid snails..here's an article about them:
http://reefkeeping.com/issues/2005-01/rs/index.php

We usually see them in 2 sizes in our tanks..the little tiny ones you have that don't cause much of an issue as the 'nets' they throw out are very small. The other size I've commonly seen are larger with a tube approximately 1/8" wide and 1 1/2" long. These have much larger nets that can be very distracting visually and can annoy your corals.
I have a heck of a collection of them in one corner of my sump (due to high flow in that area), hopefully I'll get a pic of them one day soon.

They cause no harm to your reef if you don't have too many and some fish do eat them

 

[emmanuel]

I break them at the base and then my wrasses take over

 

[NYReefer]

I break them off as well but dont have anything that eats them so they grow back.. I have one of the larger ones as well always wondered what it was. only about a half inch is sticking out of the rock, but the 'net' can extend 3-4 inches or so usually at night and when the lights first come on. luckily it is located on the underside of a cave and bothers nothing.