I see...well, perhaps I have a similar mystery as well. Any chance that you are helping your friend within a thread that I might be able to follow along with?
My Sebae is, in fact, very large. I would say that is can push a foot in diameter when it is happy enough to do so. I've had it for about two years now and even though I have done so a lot in the past, I can no longer touch it without feeling like I just rolled around in fiberglass insulation. To be perfectly honest, I spent a lot of time making sure that I keep this thing alive and never really considered the impact it might have when it grew this big. I know there really isn't a whole lot to put it in perspective, but here is a picture of this anemone. The tank is four feet wide (a 72 gallon bow front, only taller) and the clown fish is a good three inches long. Please forgive me though, this picture was taken shortly after moving to a new house and I was dealing with a subsequent hair algae issue.
By the way...I completely agree that chocolate chip stars are best kept separate from reef tanks but apparently I have some uncanny luck because I've had it for a few months and it has yet to even crawl across one of my corals. In fact, I still think it is cool to watch it eat from the glass. Anyways, thanks again!