The other day while walking out on the sand at Inskip Point I saw this Haddon's Anemone (Stichodactyla haddoni). It has a number of other common names including Saddle Anemone, Carpet Anemone, and Saddleback Carpet Sea Anemone. This one had caught a crab (in the upper right of the photo) which was still struggling rather feebly in an attempt to get free.
I have seen these anemones quite frequently out on the sand. Apparently they don't mind quite muddy environments. I have only seen relatively small ones - they can grow quite large - up to 50cm! My photos show some variation in color even in the same environment.
These Anemones can be kept in aquariums but since they are poisonous the advice is to 'handle with care'! I have seen small ones advertised on the internet for $89!