Stopped by an LPS, and noticed they had salt tanks so I decided to check them out to see what I could get and price things out. They had quite an assortment of critters and fish, including a seahorse in a tank with a mangrove shoot and some other salty shrubberies and what appeared to be some white spider-webby stuff. It was odd. Two of the girls there (who were clueless as far as fish go -- I mean, I'm clueless, these two were just wow!) stuck a pen in there to get it out and it just fell apart. I am curious...What was it? It almost looked like it was coming out of a shell in the bottom of the tank. The primary strand, a little thicker than the rest, ran from the sand to the top of the water. There were a couple of off-shoots and some on the LR, thin like...well...spider's silk.