Can anyone ID this cobweb like thing?

[Scousereefer]

So today a cobweb like fluff has appeared I am unsure whether it is good or bad. I have trochus snails which have bred before which is a possibility. I have a pair of clowns, lawnmower blenny and Diamondback goby. I did have a big conch and nassarus snails but they never come out I don't know if the conch is still alive to be honest.

 

[DocRose]

It's kind of hard to tell from the photo (for me at least), but certain fish secrete a mucus to form a barrier around them while they sleep. I've never seen a clown do it, but I'm not sure about the other fish you listed.