What's this mottled blob?

[Anonymous]

Yes, I checked the FAQ. There are two of these on the same chunk of live rock. It's slimy and somewhat rubbery to the touch. It's not hard or calcified, I don't think.

 

[John_Brandt]

Sponge. Commonly called 'chicken liver sponge' because of its texture.

 

[Anonymous]

thank you!