Are these bad?

[newfish]

I have some of these white tube things growing on my rock. They look a lot like feather dusters but the tubes look different more like some other type of worm. If its not a feather duster, are they bad. Also There are little white tubes starting to form along the back of my tank on the glass. They are the same white tubes as the thing in the picture but alot smaller for now.

 

 

Thanks for the help.

Josh

[Highland Reefer]

Tube Worms. They are very common and benefitial. Here is a link that talks about them: http://www.saltcorner.com/sections/guest/f...e/Tubeworms.htm

[lletellier]

I have a ton of them along the back of my rockwork and they continue to pop up here and there, very cool!