Fireworm VS big bristleworm

[UpsideDownPumpkin]

So I made my peace a while back with my bristleworm population but last night I saw this dude crawling about. It’s much thicker than my usual ones (even ones longer than this one are much skinnier) so I just wanted to check... Good dude or bad dude? 
 

I’ve got a fire shrimp in the tank and have read about shrimps becoming a target for large fireworms so I don’t really want to take the chance but if its harmless, I’d rather not kill it for no reason. 
 

It’s pitch black so I took the best photos I could. He’s spending the night in QT in the jug and I might make him a little QT tank while the jury decides his fate. I’ll try and get some good photos in the morning. It’s a litre jug for scale.

 

 

[Zer0]

A thick one for sure, but still a good guy. Doesn’t look like a fireworm to me.

[king aiptasia]

standard eurythoe can get over 6 inches

[Broseff]

Absolutely horrifying, but so cool. I've had bristleworms get pretty big, even with predators in the same tank. There's a good chance it's a bristleworm. Might be cool to give it a tank where it's more visible.