Tiny killer threatens giant clam, aquatic emblem of the Med

With wing-shaped shells lined with iridescent mother-of-pearl and producing the fibres of rare and delicate sea silk, the noble pen shell clam is one of the most emblematic species in the Mediterranean and a bellwether for marine environmental health. But the giant mollusc is under mortal threat from a parasite that has ravaged populations since it was identified along Spanish coasts in 2016.