colonies

I have 3 seperate colonies of these growing. They are very small, with long "tentacles" coming out of a central disc. They look almost like glass anemones, but their central discs glow almost like a florescent green under the actinic lights, and they are all in colonies. I don't have a good camera that can take close ups, sorry, but any help would be awesome

 

It's hard to tell. Are they Yellow Polyps?

 

Are they Hydroids?If they are you may want to consider intervening before they spread.

 

Colonial hydroids, try to remove them. They have very powerful stings and can take over a tank. Kalk paste is a good solution if you can get the rocks out of the tank.

 

So I need to pull the rock out, kalk paste the colonies? And do I need to let the paste completely dry before putting it back in the tank?

 

Yes!