Tiny calcareous branching growth on glass

[Phaedreef]

Can anyone ID this? I have a lot of it growing. Seems to like high flow areas.....
Always grows along surface, does not stand out from it. What you see here is about thumb-size in total.

 

[jaxredsoxfan]

Possibly some kind of tube worm? Is there an animal that protrudes out of any of the ends?

 

[Phaedreef]

I had wondered that as a possibility, but no I never see anything protrude, and also the colony or organism branches... I would have expected a tube worm, or tiny Vermetids to be straight lines.... (hey perhaps I'm wrong on that ...)