Hydroids? Can someone help me ID

[ParticleMan]

So I have a couple frags that have these things hanging on them. The zoas have never fully opened and when they have, they have these tiny pin heads. I've had them in various parts of the tank but no luck. I noticed once side has these filaments coming off and was wondering if they might be colonial hydroids. The other frag is an acan that has two spots where it has receded that have these same things. I thought it might be hair algae but now that I've seen other images online I think they are also hydroids. The other corals in the tank are fine. The acan has been in that spot for at least 2 months. If they are hydroids how can I get rid of them? Peroxide dip? I've tried to brush them off before with no luck. Thanks.

 

[DSC reef]

Looks like hydroids to me. In the past if I could remove the frag I'd scrape the hydroids off and cover the area in reef glue. I tried covering hydroids kalkwasser too if I couldn't remove the frag. It worked most of the time. If trying kalkwasser make sure its a thick paste so it sticks.