Web Spinner

[crazydave]

I've got this little guy that just appears as a little bump in the liverock. He casts out a web and then reels it back in. If I go up to the tank to quickly
he seems to retract himself into the rock. Any ideas? Thanks for the help.

 

[bigarn]

Vermetid snail ... they put the web out to catch food in the water.