Unique Corals gets them in from time to time and you can have them put you on their email list. I have had one for about 12 yrs now. I got it when it was the size of a quarter and it is now about 10 inches long. He comes out mostly at night once the lights start to dim down. Easy care, nothing special to take care of them. He does occasionally put out babies, however we have yet to see any get bigger, they tend to get eaten by something in the tank before they are large enough to fend for themselves. We see them when they first appear on the tank wall. I believe its our hermit crabs that get to them. Good luck finding one. It is one of our most talked about items in our tank. There is also a place that raises them in Hawaii but I think they are for food, I have no idea if they would sell any live.
