Unknown Growth, Can You Help Me ID?

[Glott3133]

I bought this Zoa rock and it has these red flower looking things growing on the rock. They are starting to smother the zoas, even though the zoas are growing upwards towards the light. These things are flowing with water movement, and are multiplying. Any ideas?

 

[C. Eymann]

Pic is too blurry for a confident ID, but my guess is myronemia hydroids possibly?

 

[Jamesmost]

Hydroids I think

 

[Glott3133]

I tried pulling them out and cutting them as close to the rock as I could. But they are from being completely gone. Is there a chemical that I can use to remove them?