Strange wormlike thing.

[salisbury a d]

I recently bought a beautiful rock with mushroom corals, leather corals, and more on it.
A week ago I noticed something moving under it.
I picked up the rock and it was a worm-like creature. It is a orange color with many tenacles. It sucked back into it hole. There seems to be many holes in the bottom of the rock about one half to a cm in diameter.
I waited to see it again and put the rock on others so its cave was visible. It comes out of the hole some and it has built a sand pile almost to the rock but it never leaves the rock.
What is it????
Please help.
It hasn't done any damage yet.
Adam

 

[wrassecal]

polycheate aka bristle worm. Here's a linkbristle worms

 

[salisbury a d]

It can't be a bristle worm, It has no bristles. It is also Orange in color. I don't even think it is a worm its "arms" look like a worm.( I should have been more descriptive) One time it came out farther than normal and one one of its "Arms" looked to be maybe 8 or more or less tentacles. Almost like a coral polyp.
When it builds the small sand mound it doesn't grab sand and place it. the sand just kinda glides or slides up the side of the "arm."
Call me crazy if you want but it is strange and I can't figure it out.
Adam

 

[bang guy]

Are the tentacles long & thin? (Cirratulid worm)
Or branching like a filter? (Sessile Cucumber possibly)

 

[salisbury a d]

They are very thin and when stretched out very long. It is very hard to describe since I have seen so little of it.
Wrassecal, I could not find it on the website you provided.
Adam

 

[bang guy]

Here... I pulled a large Cirratulid out of the sand and snapped a pic:

 

[wrassecal]

sorry misread your post with "tentacles" thing.

 

[nacl-h2o]

It could also be a Spaghetti worm, Cirratulids usually spend most of there time crusing around the substrate and speghettis usually spend most of there time in the rocks and usually in one pace.

 

[grouperhead]

Guy, that is really sweet! I assume it is a filter feeder? How in the heck did you get him? I'd love to get some cool stuff like that....Bo

 

[salisbury a d]

I think that is close. It is the same color but without the black bands around the tentacles.
Not sure what it looks like overall because I have only seen about 5 of the tentacles sticking out of the rock.
About the bristle worms though:
When I was adding my new sand today and arranging the rock I did discover two.
I didn't know I had them I have never seen any in my tank before.
Adam