Worm? Living in sps frag

[MTBake]

Just wondering what this is? See pic below. I've seen this maybe twice with past tanks. I have never really done anything about these and the coral sea to eventually encrust over the area. Well, now that I can get a decent pic of it, I would like an id. There are two spots on this frag with one of these creatures living in each hole.

My questions are;

What is it?

What would you do about it if on one of your frags?

Here's a few pics. You can see one coming out to feed on the left and another hole right in front. That one retracted while I was taking pics. Let me know if better pics are needed.

 

[KJ]

Coral barnacle harmless filter feeder;)

 

[MTBake]

Coral barnacle harmless filter feeder;)

Thanks for the id! Doesn't seem to bother the coral at all. I really wasn't concerned about it. Just wanted to know what it is:)

 

[KJ]

Thanks for the id! Doesn't seem to bother the coral at all. I really wasn't concerned about it. Just wanted to know what it is:)

YW;)