Giant tun (Lat. Tonna galea). Giant tun can grow to 30 cm and that makes him one of the biggest snails in the Adriatic Sea. Lives alone or in rare groups on soft and sandy or muddy bottom at a depth of 10-150 m. It feeds on echinoderms and other molluscs. The giant tun is also a luminescent species; this is an extremely rare characteristic among the prosobranch gastropods. The animal gives off light that is green-white in colour when it traverses through the water with its foot “well-extended”. From the salivary glands excretes aspartic and 2-4% sulfuric acid to dissolve the shell prey. With its attractive appearance and its size is frequently caught and sold as a souvenir. Therefore, its population in recent years has dwindled. Since 1994, this snail is protected species by law.