Is this brown stuff a sponge? Is it bad?

[Biff0rz]

While the zoas look upset, I was messing with them. During the day they are fine and out. But this stuff is spreading and I'm not sure what it is. Mostly in dimmer low flow area. Almost looks like sponge?

 

[keagan]

Looks like a harmless encrusting sponge the zoa's don't appear to be bothered by it and it appears to have oscula and inhalant pores

 

[EnterName]

I agree that it's a sponge, but just because the coral doesn't seem to be too bothered now doesn't mean it will stay unbothered.

I'm skeptical when it comes to sponges that overgrow corals and had a sponge choke some zoa polyps to death before.

I'm not sure about a proper treatment though that keeps the frag safe, is actually effective, and doesn't spread the sponge further.

 

[Biff0rz]

I agree that it's a sponge, but just because the coral doesn't seem to be too bothered now doesn't mean it will stay unbothered.

I'm skeptical when it comes to sponges that overgrow corals and had a sponge choke some zoa polyps to death before.

I'm not sure about a proper treatment though that keeps the frag safe, is actually effective, and doesn't spread the sponge further.

Hmm, fun.

 

[EnterName]

Hmm, fun.

Just to explain, why I'm struggling to find an actually good solution:

Sponges can fully regenerate from a few cells, which makes scraping them off quite ineffective. They will regrow and could theoretically spread even more this way. They recover so insanely effective and fast, that you can observe it in real-time under a microscope. Post #82 and #83 in my microscopy thread show how sponge cells are moving and "search each other" to cluster together and re-assemble after being torn apart by squashing the sample. (If you are using the mobile app and cannot jump directly to the posts, it's on page 5 the second and third post. If the videos are not working on the app you can open the page in a browser of your choice. The R2R staff is currently working on resolving this issue.)

Messing with the sponge can also hurt the zoa frag which is another problem. If you decide to take the frag out and try to scrape off some of the sponge, please wear gloves and eye protection. Just a few months ago a new palytoxin-related incident in Germany caused an experienced reefer to lose 65% of their vision/eyesight in a very painful process. Sponges are also known to produce toxins, but I'm not aware of similar incidents.

You could also try dabbing a cotton swab with vinegar/acetic acid or hydrogen peroxide directly on the sponge tissue (keeping it off the zoa obviously). This would kill cells you cannot scrape off. Another big weakness of sponges is air exposure. Air disrupts their water circulation system causing them to starve if you actually manage to get it trapped in their canals. The only issue is that for small sponges the water's surface tension and some mucus can create a protective layer making it very difficult to actually get air into the sponge without letting the frag dry too much.