Scary Worm Creature on LR

Hello All,
Well I got my first fish a couple days ago and he is doing great! Getting him a buddy tonight! Of course, after purchasing him I discovered this worm like creature sticking out of my live rock (only comes out when light is off) I wasn't able to take a pic nor locate anything similar online, although I was searching under worm, but not sure if it is actually a form of worm.

Its probably 1-2 cm diameter and stretched anywhere from 1-2 inches, looked a dark blue/black or gray, with two blue rings towards the head area. The end or mouth seemed to turn in words, then push back out (pretty gross to watch) when it pushed itself back out, these looked to be red tentacles would stick out in a circle fashion then go back in.

I am concerned that he might harm my tank mates...does ANYONE have any ideas of what the heck this thing is...if it is dangerous, how to get rid of it...its just so scary looking!!

Can someone point me in the right direction?

(Its isn't a feather duster, thats all that kept coming up online)

 

Try searching for spaghetti worm. http://www.reefkeeping.com/issues/2002-06/rs/index.php
There are many types of invertebrates that live in and around the rock. Most are harmless.
http://www.reefs.org/hhfaq/pages/main_pages/faq_rock3.htm

Jim

 

Dead giveaway peanut worm

 

i have one, heard they are beneficial. yikes, peanuts!

 

most worms in the aquarium are harmless to fish prolly about 99% of them there are only a couple but are very rare that you get harmful ones heres a site with some commonly found marine worms
http://www.mesa.edu.au/friends/seashores/worms.html

spaghetti worm these guys can multiply fast and are great scavageners for left over food ive had them with red and white tentacles
http://www.reefkeeping.com/issues/2002-06/rs/index.php