I do believe it's a eunicid of some sort.

They can grow a fair bit bigger than the beauty that you've got if you leave him be:

http://www.oregonreef.com/sub_worm.htm

It is Eunicid of some type. Without identifying the species, it is impossible to say how large it could get. I think they are incredibly common hitchikers. In fact, I've never had rock that did NOT have a few.

Mostly they are opportunistic feeders that will eat anything they can grab. I kept a similar looking one for many years that was vegetarian. He was called "Max".

Do you have a sump? I think he's destined for sump-or-refugium-life....unless you've had no problems with fish or coral loss so far?

He would be really cool to have in a species tank.:mrgreen:

I got a 60g sump but I also have a 30g QT tank running all the time so I may just keep him in there for now till I figure out what to do with him. I don't plain on getting ride of him, yet!

Would one need to know the species, in order to call it a species tank?? LMAO

I just saw one of these in my tank today. I tried to take a pic but as soon as it heard my camera's lense motor, it shot back into its cave. I read that it can retreat at 20feet/second.

http://reefkeeping.com/issues/2003-04/rs/index.php

"Contraction back into a burrow has been clocked in excess of 20 feet per second, and if only a couple of feet of the worm are visible while it is foraging, that worm can disappear, quite literally, in the blink of an eye."

There's a picture of one in the above article where the author named it Max. I wonder if it's Untamed's pictures?

That's the most disgusting thing I have ever seen....I physically gagged.

That makes me think twice when I stick my hand in my tank now. Yuk

I want one...