NEW CREATURE IN TANK ???

Question
I DISCOVER YET ANOTHER CREATURE IN MY SALTWATER FISH TANK.  ITS APPEARANCE IS BETWEEN A CATERPILLAR AND A WORM.  ITS COLOR LOOKS LIKE THE INSIDE OF A CUCUMBER AND IT HAS A BLACK MOUTH THAT APPEARS TO HAVE TEETH, HOWEVER IT IS ONLY ABOUT A INCH LONG SO I TOOK A PICTURE TO BE ABLE TO LOOK AT IN MORE DETAIL.  IT IS ATTACHED TO MY LIVE ROCK SECURELY AND HAS NOT MOVED SINCE I LAST SAW IT THIS MORNING.  DO YOU KNOW WHAT THIS CREATURE IS AND IF SO DO YOU KNOW WHAT IT EATS?  ANY HELP WOULD BE GREATLY APPRECIATED!

Answer
Hi Angela. What you may be seeing is some kind of worm. Here is a good website with lots of pictures and you may be able to identify it from there: http://home2.pacific.net.ph/~sweetyummy42/hitchhikers.html
There are so many different types of worms that no one site can possibly have pictures of them all. If you can't find anything on that site that resembles it send me a picture to my e-mail at tankgirl527@hotmail.com and I will try to find some info on it for you.