Slime algae???
 

I genuinely have no idea what this is. It’s a circular-ish dark green/brown slimy looking patch growing on the rock. I don’t see it anywhere else. While it is near the top of the tank it is in a shadowy spot. It doesn’t look stringy like the brown slime algae I found in the algae identification files. I am at a loss. It looks almost like mold. Anyone have any idea what this is, how I get rid of it, and what risk does it pose/what problems does it indicate?. These are the best images I can get. It grows in a circular pattern, is not hard stuck to the surface like coraline, and I have no idea where my live rock originated.

From the adjectives that you used, I gather you don’t like it. Use a toothbrush soaked in hydrogen peroxide and scrub it off. The hydrogen peroxide will oxidize the slime and turn to water.

I can’t tell what you have from the picture. Try this link at Reef Cleaners.
https://www.reefcleaners.org/nuisance-algae-id-guide

Thank you for your help. I actually looked there earlier and couldn’t find it. But, I think I figured out that it is an unattractive color of sponge.


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Kind of looks like an encrusting sponge, in a shady spot.

I lean toward Michael's thought, I also think it looks like a sponge. I personally encourage sponge growth.

Yes
 

I agree with you both. After looking it up I also think sponge. I have yellow sponge elsewhere, I just never saw sponge that color. Glad I don’t have to fight a pest!!

Thanks so much!