Spider sack ID?

[Nighthawk4u]

Anyone know what this is? I've read a lot of the other post, I'm figuring it's either snail eggs, or I should be looking for a spider with a snorkel and fins.........
If you notice there are two of them in the second picture, One is just below the big one, in a hole. Looks like cotton, but obviously attached there by something.

 

[RJT]

Its a sponge. Safe, filters the water