Spider web in my sump?!

[lickyricky]

Well I know it’s not from a spider but what is this?! It’s growing in my sump between two rocks. I noticed a few little bugs and some bigger centipede things (would be good to know what these are too!) crawling on the “web” and elsewhere in my sump.

Any ideas?

 

[mtraylor]

sponge

 

[KJ]

Sponge.

 

[lickyricky]

Sponge.

Good? Bad?

 

[KJ]

Harmless filter feeder.

 

[mtraylor]

sponges are good.