The Noble pen shell (Lat. Pinna nobilis) is the largest bivalve in the Mediterranean and Adriatic seas respectively. Endemic to the Mediterranean Sea, it has disappeared from many zones with high anthropic impact, pollution, trawling and rarefaction of the seagrass meadows. Lives on sand and muddy bottoms of shallow nearshore regions. The anterior pointed part of the shell being burrowed in the sediment. Lives at depths from 1 to 30 m. Grows to the size of 120 cm. Being a filter-feeder it thrives more easily, creating at times thick colonies, in all those positions with constant and moderate water flow where it can easily intercept the nutrients and the plankton of which it nourishes. In 2016, there was an outbreak of a disease that caused the mortality of 99% of population in Spain. The cause of the disease is a newly discovered pathogen, Haplosporidium pinnae and it is posing a serious threat to the survival of the species. By 2019, mortality spots have been detected in Greece, Croatia, Turkey, Tunisia, France and Morocco. In the Trieste area, considerable efforts have also been made to conserve the deposits since 2020. In the past, Pinna nobilis has been threatened with extinction, due in part to fishing, incidental killing by trawling and anchoring, and the decline in seagrass fields; pollution kills eggs, larvae, and adult mussels. In December 2019, Pinna nobilis has entered the IUCN Red List as critically endangered.