Hydroids?

[BadCrab]

Noticed something growing next to, and irritating, a few zoas.
They're growing quicker than I'm comfortable with.

Are these a species of hydroid?
If so, could I scrub the area with a toothbrush during water changes as an effective solution?

 

[evolved]

It's a digitate hydroid - there's a lot of different types. Typically, they don't sting too bad, and the population ends up being self-limiting based on available food.

I've had smaller ones in past tanks, but only in shaded regions. Eventually, they all died off - but that did take many months.

If you've got just that patch, I'd just epoxy over or kalk paste smear them.