Very small Polyps? ID Please

I have 3 or 4 colonies of these growing on my rocks. They are very small and grow in patches. They have a hard tube and a polyp that extends almost like a Zoa and will retract when disturbed. They grow very slow. Any Idea's?

 

Pics would help a lot.

 

sorry had trouble posting the pics. Hope this is better.

 

Excellent pictures, I have some in my tank and will ride along for an ID. They might be colonial hydroids. They are said to pack a wallop.

 

I will try to get a better shot.

 

Here are the links to the original photos on webshots. Best I can do for now as my lights are off for the night.

ID1 pictures from aquatic photos on webshots

ID2 pictures from aquatic photos on webshots

 

New Pics.

 

if you touch them and they withdraw into a hard tube they could be the polyp stage of a jellyfish, i have had those in my tanks many times. Species is Nausithoe sp
If not i would go for hydriod