Can someone help id me these white projections on live rock?

[reefer_87]

I am wondering if I could use this live rock for cycling dry rock for my new reef tank. However, I see these white projections that I am not sure about. I have bristle worms in my old tank which I am not particularly averse of and hence ok with it. But not sure about these and if they are harmful.

 

[guylaga]

Hard to tell, could either be spirorbid worms which are harmless or vermited snails which can be a pest.

 

[guylaga]

double post