What is this spider web like stuff?

[Jenny mitchell]

I have got up today to find spider web like stuff throughout my tank, what could it be? We did a water change yesterday and there was none then, but it's everywhere today! We have a regal tang, 3 chromis, 2 Picasso clown fish, a coral beauty, 2 pj cardinals, an emporer Cardinal, some snails, red legged hermit crabs, an emerald crab, a few shrimp, a feather duster and an urchin. Any ideas! I posted a few weeks ago about some white tube like things growing out of my live rock, but the though was that they are some sort of sponge, but they seem to have decreased in number, or have died?

 

[JohnVH]

Looks like it could be vermatid snail web possibly or some kind of bacterial bloom. The only times I've ever seen something like that myself was from a dying or damaged coral that oozed a mucous like substance.