Black rubbery growth on bottom of live Rock

[jtroxel1]

I found this shifting some rocks near the bottom of my aquascape today and cannot find anything that resembles this using Google lens or a Google search.
It's thick, maybe 1/4" in some places.
It does not brush off nor peel off (at least easily - I have not tried a knife or pliers)
It has a very shiny surface
If I didn't know better, I would think it had been "tool-dipped" in that black plastic coating.
First time I've noticed it, so I cannot comment on it's rate of spread; being under the rock it does not seem to be attacking anything.
If it's a sponge, it's as weird as anything I've come across in a tank.
Any help identifying it, and next steps if it's evil.

Thanks!

 

[exnisstech]

Looks like maybe a sponge. I have quite a bit a black sponges. Mine have not been a problem and only grow in dark areas.

 

[stevelee]

I found this shifting some rocks near the bottom of my aquascape today and cannot find anything that resembles this using Google lens or a Google search.
It's thick, maybe 1/4" in some places.
It does not brush off nor peel off (at least easily - I have not tried a knife or pliers)
It has a very shiny surface
If I didn't know better, I would think it had been "tool-dipped" in that black plastic coating.
First time I've noticed it, so I cannot comment on it's rate of spread; being under the rock it does not seem to be attacking anything.
If it's a sponge, it's as weird as anything I've come across in a tank.
Any help identifying it, and next steps if it's evil.

Thanks!

spotify premium versão antiga

I have noticed that a black growth is spreading all over my live rock. It does not show up in pictures, but in the tank, it is very noticeable. It looks almost like a spider web, and tears very easily. When you tear it, bubbles come out from behind it. When you tear a small piece off and take it out of the water, it looks like a black slimy substance. The slime spreads all over the crevices in the live rock and spreads from rock to rock. Sorry about the bad descriptions, but does anyone have any idea what this stuff could be? Thanks.

 

[Kasrift]

I found this shifting some rocks near the bottom of my aquascape today and cannot find anything that resembles this using Google lens or a Google search.
It's thick, maybe 1/4" in some places.
It does not brush off nor peel off (at least easily - I have not tried a knife or pliers)
It has a very shiny surface
If I didn't know better, I would think it had been "tool-dipped" in that black plastic coating.
First time I've noticed it, so I cannot comment on it's rate of spread; being under the rock it does not seem to be attacking anything.
If it's a sponge, it's as weird as anything I've come across in a tank.
Any help identifying it, and next steps if it's evil.

Thanks!

Black sponge. Some can be invasive. I had one overrun an acan.