Resolved Assumed tiny tube worm, Nope. Colonial hydroids

A long time back I found my Black mithrax crab eating these. He wiped out the colony. A couples weeks ago I noticed a small colony of about 30 in a 1/2 inch square area. Today I found 2 more colonies each in about a 1/4 inch square area having about 15 each in them. All three colonies are in three completely diffrent area's of the tank. They are extreamly small. Tubes are about 1/8 of an inch tall and slightly smaller then the thickness of a thumbtack pin. Tubes are soft and flexable but stand upright. They seem to always anchor in cavities. The tentacles are not feathery but more like an anemone. Touching or waving water suddenly near by makes them 'instantly' retract. The picture shows both retracted and displayed. Can someone ID please.

 

Colonial hydroids.

 

Rught ro rorge!
Thank you. I think :?

 

Wish I still had my Mithrax crab

Any other preditors? Or is paste the best answer?

 

If you can get some kalk into that hole that would be the fastest kill. I had some that fluoresced green. They never bothered anything so I left them alone.