Anemone are primitive animals belonging to the phylum variously known as Cnidaria. Sea Anemones are single, mobile polyps with no skeleton that come in many sizes and colours. They range from about 1 centimetre in diameter to about 50 centimetres but a few can grow to more than 1.8 metres across. They have a squat, columnar body with radial symmetry, a single opening at the mouth and a sucker-like base. There is a circle of stinging tentacles, arranged in multiples of 6, surrounding the mouth which are used for feeding and for protection.