Marine scientists reported a remarkable rise in the noble pen shell population, previously endangered by a severe illness in the Mediterranean in 2016, which drastically reduced their numbers. Only about 10 of these clams were seen surviving in the Adriatic Sea near Croatia until recently. However, in 2022, the discovery of 20 clams near the Istria peninsula’s north shore surprised experts, causing significant astonishment.

Sandro Dujmovic, associated with the Natura Histrica organization that takes care of Istria’s protected areas, was astonished, expressing how unbelievable it seemed that these clams had survived. In 2023, scientists gathered about 100 young noble pen shell specimens and moved them to an aquarium, showing that they could reproduce. These clams, which can grow up to 4 feet (120 cm) in shell size, are vital for the environment as they clean seawater and help other sea creatures grow. To keep them safe, they are kept in a special place at the Pula aquarium, where they are shielded from parasites. Biologist Nikolina Premate stressed the importance of a clean environment for these clams to grow well and adjust before possibly returning to the sea. Although the exact reason for their resurgence is uncertain, the government of Croatia has set aside money for more research. Dujmovic highlighted the joint work of various groups along the Adriatic coast, monitoring and protecting these clams.