Please help to identify this worm

[FreakPrism]

So today I was installing a gas strut on my canopy door and turned on my hallway lights at night. It was interesting to see as the tank was in "night mode". I caught the worm in the picture below on one of the rocks and then it eventually moved back into a rock hole. Can you please help identify what this is and whether it is beneficial or not. I am assuming it came onboard a frag about 2 weeks back despite me using Revive but not sure as first time I saw it.

 

[Alaeriel]

Looks to me like a type of bristleworm? Could definitely be wrong.

 

[Bricks]

Looks like a bristle worm to me! I've has one as a hitchhiker and kept it because I heard it was ok to have on my CUC. Ended up getting rid of it because I didn't want anything in my tank that could possibly harm any of my inhabitants.

 

[v3v3]

Small bristleworm.