Bristle Worm of Some Sort?

[VR28man]

So I was browsing tampabaysaltwater.com @liverock 's hitchhiker database and found this worm. I think I've seen the exact same thing - it's a very sensitive, nasty looking thing that hides in holes in the live rock and runs back, I believe into the substrate, very quickly. (and thus hard to get a photograph, which is why I'm reusing theirs)

Any guesses?

 

[DSC reef]

Possibly a type syllidae

 

[Lovemyreef2015]

+1^^

 

[VR28man]

Thanks! It's as good of a guess as one can make from the picture. Not very helpful, of course (since I don't have a microscope copy picture that I can give). But at least it shows that it's at the very least not necessarily harmful to the rest of the tank. This came as a hitchiker from who-knows-where - most probably a dipped frag.