Funny Critter

[BigNEMO]

The other day I saw a funny looking critter in my tank sitting on some live rock. By the time I got my digital camera he was gone. So I will describe it.
1/2" wide x long
1/16" thick
Grayish looking

The funny thing was it had a hair like whip that it would send out up to 15" long then pull it back in to its body. Anyone ever see something like this?
It looked like it was filter feeding.

 

[steve-s]

Either a vermetid snail or a spaghetti worm. The vermetid snail builds a narrow calcerous tube like a feather duster and excretes a mucus web to catch detritus and other foods that float by.

Cheers
Steve