I have a Bristle Worm that came in on a live rock about 5 months ago. I researched it and found it to be good for the tank as long as you don't touch it. I never normaly see it being nocturnal. Last night it came out as soon as the lights went out. The worm got HUGE. It was about 5 to 6 inches long. Should I begin to worry about this? How big do they get? Will they hurt anything?