looks like the normal brown zenia. they spread easily if you put enough flow over them.
Look like nice Live rock, where did you get it from?
I also thought they were xenia, but they close up and open up randomly. Not sure if that normal for xenia?
sounds about right. well they are a nice thing to have in the tank
im not wearing my glasses, but even i can see separate polyps coming from each tube on the rocks definitely not tubeworm. pictures are a bit blury. try zooming out just a bit.
Looks like a calcified tube at the base though, and he said they retract into a tube. Corals don't live in tubes.
+1 for more pics.