Any ID on this?

[Knr499]

Found this on the back of a rock in front of my overflow. Gets zero light. Can’t reach it to get a sample. Had to use flashlight to get picture. Approximately 6 inches across for reference and gray in color. Thanks

 

[EeyoreIsMySpiritAnimal]

It's a sponge. Harmless filter feeder.

 

[Crabs McJones]

Agree, sponge

 

[Knr499]

I was thinking that but never saw one that big, lol. Thanks.

 

[dakoop]

The blob