Bristleworm in tank

Ok everyong...lets just remember that not all bristle worms eat corals...infact most of them are very happy eating left overs in a tank

 

I have several bristleworms in a 10 gallon and never have seen them do any harm to corals, fish or any other inhabitants.

 

I will never EVER EVER get used to these things! I get the willies each morning when I've had to empty the trap. Most of the big ones are out now (had to get them with a net, they wouldn't fit in the trap) and it just literally gave me anxiety problems getting them out. I'm so pathetic when it comes to things that squirm around though

 

I recently discovered a large (>2 inch), fat bristleworm in my 45 gallon. He must have been there a while, as I have not added any creatures to my tank in 6 months.
So, how do you tell a good bristleworm from a bad one?

 

Here's a picture.