I do not think its a waratah anemone, well let me say this instead.. it shouldnt be a waratah anemone, they are a cold water species. If it is it needs very bright lighting metal halides to be exact and a tank temp in the 58 to 60* mark so a chiller is a must. Having said that, it sure does look like one though.
My next guess would be Cladactella Manni Aka Hawaiian Maroon Anemone, Manns Anemone or Manni Anemone. They sell them here on SWF. Does it have verracae on its under side of its disk or foot? These anemones require very turbulent water to keep them happy and their is very little success in the home aquarium.
In either case which ever one it is. If it is any one of the 2 I mentioned they are both very hard species to care for.