Help with this thin white lines

[ariverajr.1992]

What is this. I never seen this before on my torch?it’s also on my snail. They don’t move at all but it’s hard and bumpy? They are like white thin hard lines? Please help

 

[Rtaylor]

Likely some sort of tube worm like a feather duster

 

[ariverajr.1992]

Likely some sort of tube worm like a feather duster

Are they dangerous to the tank?

 

[Reefkeepers Archive]

Featherdusters, harmless/beneficial filter-feeders