venwu225,
I've been thinking about keeping it. I have no evidence that it has harmed anything in my tank. All my zoas, palys, shrooms, rics, etc. have been fine. I have not put any new rock in my tank for the past two years. All rock is pre-Hurricane Katrina. No purchase of anything large enough for the worm to hid in, so I think he has been with me for some time. The large rock he is living in was until recently a base rock and is now in the top center of my tank, so maybe that is why I am just seeing it. If I decide to get rid of it, I'm going to try and catch it alive and find a home, maybe in my sump. Who knows.
ckekelle, I ran across the link you posted. It is hard to believe something like that can live in one of our tanks. Reminds me of the movie Tremors.