Ok people....what the heck is this stuff? It is milky in color and very very very delicate. It appears as if it is a spider web. Yesterday it was broken up (it was covering a hole in the rock), now today it is completely repaired and the hole is covered again. I saw it on the rock when I bought it and asked the guy at the LFS
what it was. He said he didn't know. Can you people tell me what this is?