Unidentified worm? Good or bad?

[Wade]

I picked up some new coral at a dealer in Vancouver, a day later I found this worm in my tank crawling in live rock. It is about 6 inches long and a little thiner than a pencile. Can anyone identify it? Is it harmful to my reef tank?

[/img]http://www.canreef.com/photopost/showphoto.php?photo=1424[img]

I hope the picture is going to show up