Growth on rocks/back wall?

[JeffJ]

Hey Guys -Can someone please ID what these growths are? Good or bad? They look like very small saltwater crawfish holes.Thanks!jeffView attachment 7782

 

[reeferjim]

I'm not sure what they're called, but I have them too, for several years now, some kind of filter feeder. 

 

[jenkinscrew]

My guess is spirorbid worms, they start very small. I have them too. Just a filter feeder. https://www.melevsreef.com/critter/spirorbid-worms

 

[JeffJ]

Thanks, Chris!I appreciate the info and am glad to hear that they are a normal part of a healthy tank. Jeff