Edible sea urchin  (Echinus esculentus)

The edible or common sea urchin has a large, rounded 'shell', which is actually an external skeleton, correctly called a 'test', composed of calcareous plates. It is usually pinkish-red in colour but more rarely may be shades of yellow, green or purple (2). The shape of the test varies depending on the depth of the water; those of individuals living in shallow water tend to be more flat than those of individuals living in deep water (3). The Latin name for the genus 'Echinus' derives from the Greek for 'spiny'; the test bristles with many protective reddish spines with lilac coloured tips (2).