Fin

It is a bivalve mollusk of the genus Pinna. To feed and breathe, the mollusk pumps water into the mantle cavity through an inhaling siphon and then emits it through an exhaling one. The valves have a rounded posterior margin and have about 20 radial ribs with channel-shaped scales. Still surviving today is the species Pinna nobilis with a typical brown color with lighter scales; the interior is shiny with a mother-of-pearl front. They can live more than 20 years and reach one meter in length, but the average shell size of an adult specimen is around 65 cm. It has a fairly rapid development in the early years of life, averaging 10 cm per year; upon reaching sexual maturity, around 40 cm, growth slows down and settles at about 10 cm every 3 years.