ID-White string like structures

[Bonsai reef]

I see these white stringy thing on the hammer stem. Are these any kind of worm or part of its skeleton? Noticed this in my acan skeleton too. They don’t move and the hammer is healthy otherwise. Pics below when its not open /lights off vs open

 

[Flippers4pups]

Common tube worm. Harmless.

 

[homer1475]

Common tube worm. Harmless.

+1

 

[Bonsai reef]

Will it multiply rapidly? Are they good for the tank eco system? If not, whats the best way to eradicate them

 

[homer1475]

Yes they are good for your system. They are harmless filter feeders. Think of them like tiny free additions to your CUC, except they "clean" the water.