I’m not sure if this is a type of coral or tube worm.

[spnorman1989]

 

[KJ]

Colonial hydroids.

 

[spnorman1989]

Colonial hydroids.

Thanks. That’s is definitely what they are. I’ll keep and eye on them to see if they become problematic.

 

[KJ]

Thanks. That’s is definitely what they are. I’ll keep and eye on them to see if they become problematic.

YW.

 

[Crashnt24]

I have had some growing on a patch of rock for 3 years now. It just recently started to spread to other areas of the tank. I would suggest removing them before they become a issue in other areas. They aren't ugly or super fast spreading but they can start taking up space for corals down the road, especially if they start spreading.