Coming from my rock.

Question
I have a large rock in my new coral tank and it has a tentical about 2 inches long that comes out only when the light is OFF, it is as straigt as an arrow but when i turn the light on it goes curly like a snake back into the rock. I don't even know what or how big it is because the whole thing has never came out completely. It's came out of 2 different holes in the rock... It is not a bristle worm it looks kinda like a barb off of a sea urchin but much longer and it only looks stiff like that until i turn thie light on and it gets wiggly and slithers fully back into the rock. I tried to get a pic but no sucess yet. Does anybody have any idea?

Answer
Is it striped, by chance?  Jeff, it is probably the tentacle of a starfish.  They are called Brittlestarfish.  I have tons of them. :)

They are bristle stars.  Let me find you an image...two tentacles tells me it's not a bristleworm.

http://assets.saltwaterfish.com.s3.amazonaws.com/5/56/525x525px-LL-56443a81_vbat...

Is that what's hanging out?  It's a microstarfish's leg. :)

Happy fish-keeping.

Renee