Mollusc mass mortality event: can Spain’s giant fan mussels recover?

Pinna nobilis is vital to the Mediterranean ecosystem, but since 2016 numbers have plummeted by 99.9% - and saving it from extinction is no easy task

In the shallow waters and seagrass meadow of Spain's Ebro delta, there are almost no solid surfaces for creatures to latch on to. That's where the fan mussel (Pinna nobilis) comes in. Sponges, sea anemones, algae and lifeforms not found on any other surface in the area live on its shell, while octopus, oysters and some fish live inside it.

The bivalve, also known as the noble pen shell, is unique to the Mediterranean and is the second largest in the world, with some specimens reaching a metre in length over a 15-year lifespan. It plays a crucial role in water filtration as well as providing a home for an array of underwater creatures.