What’s this cloudy thing?

[calvi]

Hello,

I hope you can help me identify this cloudy looking thing that live under my rock.
I’m not taking about the Vermetid snail. I know that’s a problem too

 

[35ppt]

Redacted

 

[kchristensen8064]

Being on the underside of your rock from what I can tell. I'd say it's a sponge of some sort.