What is this Coral?

[Snappy]

Originally Posted by justinl

Greg, the ones you see on the rocks probably just technically aren't xmas tree worms...

Actually yes they are, I don't want to sound like a jerk but I think I have enough experience both in this hobby and as a diver to know the difference between a feather duster and a xmas tree worm. They are very commom in orange, red, blue and grey in the Puerto Vallarta area and host in solid rock. They bore a hole just like they do in the corals. I recommend you go diving at Los Arcos for example and then come back and tell me they aren't xmas tree worms.
But if you go can I come too? We'll have a blast..

I've never even heard of this species...how does it differ from Porites? It looks VERY similar. If this is true (and I doubt it very little), then I bet there are A LOT of misidentified Porites out there!

It is an LPS and Porites is SPS, the polyps are completely different. As they get bigger the difference if more prodominant.
Here is a picture (magnified) I just took of mine. At night the regular polyps start to retract and if you look closely you'll see sweepers starting to extend in a few places. In a few more hours it will be a mass of tenticles.