Just a bristle worm...right?

[Rev_Svejk]

So I've been setting a trap to try and catch a biggish crab that showed itself in my 60l nano randomly a couple days ago.  Don't know where he's been hiding but geez, it was a big black gorilla crab I believe.  Instead I've been catching my cleaner shrimp and this guy is coming round to the bottle opening.  Freaked me right out the other night when I couldn't see him so well in the dark.  Stuck a red led on the lid so I could observe him.  He's about 8inches to a foot long I guess.  He seems to keep himself anchored in the rock so I don't see the whole body.  Definitely nocturnal...whaddya think?  I'm ho.ping it's just a freakishly large bristle worm