What's this on my Zoas?

This rock came straight from the ocean.
It looks somewhat like brown cotton buds on the rock with zoanthids.
Could it be a type of algae?
Is it safe to put into my DT?

 

Look like colonial hydroids to me. I'd avoid adding that to my DT if they are.

 

It may be an algae, it looks as if you have it in a holding tank so keep it in there a while and see if it spreads, although, the display will have more nutrients and may cause it to spread.

 

It kinda does look like hydroids but I'm not 100% sure of that.

It is in a holding tank. It has been there for a month or so. No Spreading or die off has occurred.

 

I just went to frag some shrooms and I notice that they have spread onto some surfaces in the tank.

 

Do a Google image search for brown hydroids. I'm pretty sure that's what you have.

 

good guess

 

Yes it is.. Brown Hydroids.
And here I am, thinking that they're harmless hitchhiker. I'll try my best to prune them out but I don't know if I'd be able get them all out: