Pinna nobles is a symbol of beauty, rarity, longevity and sustainability
Pinna nobles, common name the noble pen shell is a specie endemic to the Mediterranean sea.
The bivalve shell is usually 30–50 cm (1.0–1.6 ft) long. It is relatively fragile to shell damage and purify the marine pollution. It attaches itself to rocks using a strong byssus composed of many silk-like threads which used to be made into cloth. The animal secretes these fibres from its byssus gland; they consist of keratin and other proteins. The inside of the shell is lined with brilliant mother-of-pearl.
In recent years, Pinna nobles has become threatened with extinction and has been listed as an endangered species in the Mediterranean Sea.
Sea silk is extremely fine and rare. The byssus or filaments (which can be up to 6 cm long) are spun and, when treated with lemon juice, turn a golden color, which never fades.