Black Sponge?

[moriartyko]

I have what I think is a black encrusting sponge. It's rubbery to the touch and spreading on the underside of some rock. All at once, bubbles appeared on it for a few days. Then the bubbles released into the water column and went all over the place. I have no freaking idea what they are. I haven't found anything about sponges having and releasing bubbles. I added one pic w/o the bubbles and one w/ the bubbles. Can anyone identify my sponge and tell what the bubbles mean?

 

[SeaCucumberFan]

It may be bubble algae but I also have had a similar sponge in my sump

 

[moriartyko]

Thanks, SeaCuke - did your sponge also get and release bubbles?

 

[Ron Reefman]

I don't know what it is for sure, but I seriously doubt that it's bubble algae. I've seen green and red bubble algae, never black. Every bubble algae I've seen is round, or as round as it can be if it grows into a tight space. This stuff isn't very round. Algae does photosynthesis and this is growing under a rock so no (or not much) light to do photosynthesis.

Did the 'bubbles that were released float to the surface? Or were they less buoyant and drifted in the water column? Did you pull a bubble out and try popping it to see what was inside?

 

[moriartyko]

They floated around the water column. I didn't try capturing one and popping it, but I will when I see one. Their numbers have dwindled and there are some small patches under the area where they were that appear to be the rock. In other words, it appears that some of the sponge died off. But, even if that is what happened, it wasn't a lot.