Curious what are these?
 

https://fbcdn-sphotos-c-a.akamaihd.n...68466812_n.jpg
I have these on my Emerald on Fires and apart from looking like a plague they have never seemed to bother the zoa? Curious what they are. They don't affect any of my other zoas or in the tank anywhere.

looks like some sort of sponge

Looks like maybe dead colonial hydroid tubes? If so, and no "fan" comes out the end, then they are likely dead hydroids (good thing). If the "fan" does come out the end, they are similar to Aiptasia in that they sting surrounding corals and may spread rapidly. Are the tubes soft? Colonial hydroids have soft tubes.

A pic with the "fan" out (they appear clear when the hydroid is retracted or dead):
http://img52.imageshack.us/img52/1243/hydroids.jpg

I was thinking along the lines of a sponge as well but they are tube like:question:

Hey myka,

I have never seen them any other colour then white, and never have had anything extending outwards.

I would tweeze or scrape off anything on a zoa plug thats not a zoa,not a lot of realestate there!:biggrin:

I do clear the zoa with a razor blade of these things and a week later they're back! To be honest when I got this frag there was nothing and they didn't grow and non existent, It wasn't even coloured and struggling when I got it 5-6 months ago, since its regained its color and thrived these things have been growing?>

They could have been dead when you bought the frag. I have a few dead colonies about that size on some of my live rock.

Good advice. :)

I will get scraping again, haha

Also posted on RC see if anyone over there might know..