Can anyone tell me what this is?

[J670]

What is the white residue next to the nem?

 

[ryshark]

hard to see, but looks like a sponge; which is harmless.

 

[J670]

Sorry iPhone cam is not great.

 

[Hinds04]

I have something simialr on a rock around my feather duster. I would also assume a sponge of some type. Mine is a cloudy milky white color...

 

[J670]

Yeah it's kinda weird. It looks like it has small tentacles like the nem next to it. It just doesn't move