Trying to identify and then how to control?

[GuppyHJD]

These little filter feeders arrived in my tank on the frag plug of a gorgonian. At first there were maybe a dozen. Now they have colonized an area about the size of a lime. I do not want them to spread and cover my rockscape. So first - what are they? Then any suggestions on how to control or remove them? Thank you

 

[Sharkbait19]

Hydroids
I’m not sure how to remove them, I think the aptasia methods work though.

 

[GuppyHJD]

I am looking at epoxy, make a pancake and wrap around the rock, covering the hydroids? OR superglue balls?

 

[afrokobe]

Colonial hyroids. I have some myself too. Mine hasn't spread as badly as yours though. I'm considering using some aptaisia x