What might this be?

[Lksheppa]

Just noticed this on the live rock. I'm unsure what it is or if it might indicate anything in the tank??

 

[Lksheppa]

http://imgur.com/lrEuOTB

 

[AlSimmons]

I'm not exactly sure what I'm supposed to be looking at in the picture you posted, but the link below might help.

https://www.lionfishlair.com/hitchhikers-guide/

 

[Lksheppa]

Sorry! It's the dark patch of something or other on the live rock. It has a softer surface (I prodded it with our little "poker") and I'm unsure what it is.

 

[AlSimmons]

Oh ok. I see it now... It's probably just a harmless sponge of some sort. No worries.

 

[Lksheppa]

Alright, thank ya!!

 

[jrosales91]

Looks life the same stuff I have and I haven't been able to figure out what it is or how to clean it.