Sponge???

[Floyd R Turbo]

This was found on the back side of a couple pieces of LR in a customers tank. He turned both large rocks around this morning and found them. The look like they could be a sponge of some kind, any ideas about what they are exactly?

We also found a few more smaller ones, if you can see them.

This tank is well established but suffered a setback on all corals from lack of maintenance - high Nitrates (over 200) and lighting problems, phosphates, etc. I just got done with a series of PWCs and cleaning to bring Nitrates down to 50, then did a 50% PWC today so they should be below 30, and everything is now coming back alive, but he doesn't ever remember seeing these before. They are most definitely alive, because during the PWC all the 'seams' sealed up and there were only a few holes open.

 

[chipmunkofdoom2]

Yes, they appear to be like the sponges I have. They're thin and flimy in places in my tank too. I'm surprised they survived the bad conditions.

 

[Floyd R Turbo]

Yeah, the nitrates were down to about 40-50 after this series of PWCs in December: 13%, 13%, (during major sump cleaning), 10% (leftover water), 25%, 25%, 25%. Just in case anyone is wondering, this is not the 135 FOWLR I have the journal on, this is a different reef tank I am also working on...Journal probably coming soon.

 

[BigAl07]

Floyd if you can step up the volume of WC you will get them down quicker.

That sponge looks a LOT like the ones I just scraped from my tank last week. They only grew in shadows and over-hangs and were kind of cool for a long time until.... They started becoming aggressive and over growing some Zoas and other coral that weren't in the shadows. Just keep an eye out for accelerated growth.