Weirdness in my tank?

[sk716]

Six weeks ago I bought my first live rock and went about converting my 10 gallon saltwater tank into a reef tank. Four days ago I spotted my first hitchhiker, I think it was a ghost shrimp.
Today, I bought a few new live rocks, and pulled a piece of dead coral I had in for decoration out. Wrapped around the base of this coral, down in the crushed coral I discovered what looks like a starfish arm. It's not segmented like a bristleworm and is kind of tapered with 'thorns' on it. It squiggled off like a worm.
Is it a bristleworm?

EDIT: Have been doing some research into starfish. Looks like I got a piece of one of the brittle stars. Pretty long piece though, about 2 1/2 inches long. Can't seem to identify it through pic's I've seen, it's kind of pinkish with light yellowish thorns. It's already hiding under a rock again now.

 

[fishfanatic2]

It could be some sort of sea cucumber, or more likely a nudibranch. They are pretty, but the cucum's spew their guts into the water if annoyed and kill everything. Nudibranch's are amazing but are often EXTREMELY specialized in their eating habits.

 

[klingsa]

A picture would help a lot, but it sounds to me like a bristleworm. I have hundreds of them in 75 gallons. The kind I have are also called fireworms, but are harmless to the aquarium. They help keep the sand stirred up, and consume detritus. The segments can be identified by each bristle that sticks out, one on each side of the segment. They can sometimes have a blue streak in the very middle of the body, under certain light, when they get big enough. May not be what you have, but if it responded so quickly to being moved (you say it squiggled off like a worm) then it is probably not a starfish arm. Anyway, doesn't sound harmful to me.