What are these forming on the rock?

[Dev’s Reef]

Hello R2R community, I am new to the forum and am excited.
I have had my Evo 13.5 for a couple of years now and would like to start adding in some corals. I had noticed on the rocks a few small white tubes forming in the crevasses of the rocks, these are hard and have no movement. Last night I had picked up my rocks to rearrange and noticed a bunch of them on the bottom. I would like to know if they could cause any harm to my future corals and how to remove these as they are starting to multiply.

Thanks!

 

[Mark Novack]

Serpulidae. Feather duster worms in a calcareous tube. They are not a harmful pest.