What is this growing on my rocks?

[Lester Verano]

the small cluster of super small greenish matter on my rock. they appear to have hairs on them, are green, and shaped like ultra small zoanthids. what are these? are they harmful to my reef tank? thanks. sorry that was the bet pic I could get.

 

[ISpeakForTheSeas]

Probably colonial hydroids (though I can’t tell for sure from the pic).

 

[Lester Verano]

Probably colonial hydroids (though I can’t tell for sure from the pic).

yes I think that is them. thanks!

 

[EeyoreIsMySpiritAnimal]

yes I think that is them. thanks!

You want to get rid of these ASAP