if the bristle worms are killing your anemone or corals the thing must be half a foot long or bigger just stab it with something.... I think this unlikley, though, I have seen one over a foot once. in my friends 120. he just baited it out with food and netted it. traps, six lined wrasses, pseudochromis fridmani, and netting all work. I just scoop the big ones out by hand. They are benificial sand shifters and detritivores. (I also think they are cool looking) I know kinda weird.