Mysterious new starfish/species in my tank HELP ID!

My girlfriend was looking around my 10gal nano today, and found a new living "thing" in my tank, ive only ever had my clown, skunk and blood shrimp in my tank, we saw it slowly coming out from under a rock, the pictures is as far as it has come out, its about an inch-two inches long from the one tentacle we can see anyways. I have no idea what is is, where it came from and how it is so big, I also did a complete aqua-scape a few days ago and didnt see it, so it must be living in the rock? I also tried to touch it, and it jolted back in really fast, so I dont think it could be a type of starfish? What do you guys think it is?

 

It is a type of worm, See if you can get a pic of the mouth area it should help with the ID.

 

some kind of bristle worm by the looks of it

 

I thought I was gonna see some kind of amazing new species! lol

 

Bristleworm. Good thing you didn't manage to touch it!

 

Yep! Bristleworm for sure! Great for your tank and yes they live in the holes of your LR

 

Sorry for getting your hopes up lol very misleading title aha

 

So this is a good thing?

 

The bristles would've come off in your fingers. Ever touch fiberglass?

 

arrow crabs eat them.