The shell of this species grows as large as 10 cm (3.9 in) in length and 6.5 cm (2.6 in) in width. This flattened, oval shell is an ear-shaped spiral with a mottled outer surface. At the bottom margin of the shell, there is a curving row of five to seven slightly raised respiratory apertures, through which the mantle extends with short, exhalant siphons. As the animal and the shell grow, new holes are formed and the older holes are sealed off. These holes collectively make up what is known as the selenizone, which forms as the shell grows. The inner surface of the shell has a thick layer of iridescent mother-of-pearl.
The large and muscular foot has numerous tentacles at the epipodium (the lateral grooves between the foot and the mantle).
Ormers are considered a great delicacy in the Channel Islands. Overfishing has led to a dramatic depletion in numbers since the latter half of the 19th century.
"Ormering" is now strictly regulated in order to preserve stocks. The gathering of ormers is now restricted to a number of "ormering tides", from January 1 to April 30, which occur on the full or new moon and two days following that. No ormers may be taken from the beach that are under 80 mm in shell length (90 mm in Jersey). Gatherers are not allowed to wear wetsuits or even put their heads underwater. Any breach of these laws is a criminal offence which can lead to a fine of up to £5,000 or six months in prison.[1]
The demand for ormers is such that they led to the world's first underwater arrest, when a Mr. Kempthorne-Leigh of Guernsey was illegally diving for ormers, and was arrested by a police officer in full diving gear.[citation needed]
