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.
The base of the sea anemone is a pedal disc or foot that attaches firmly to solid objects like rocks and coral, or anchors it to the sea floor. Some anemones have small wart-like projections called verrucae that are arranged in rows and are usually a different colour to the anemone.
Sea anemones have very simple internal anatomy. They have a central gastrovascular cavity (or stomach) with only one opening that functions as both the mouth and the anus. Sea anemones have no visible sense organs but are quite capable of distinguishing between edible and inedible materials.