Keen diver Yusuke Fukami fulfilled a personal dream by snapping a cartoon-like Costasiella sea slug while in Bali in the last decade of December 2024. (Photo by Yusuke Fukami/South West News Service)

A pine marten – one of a few wild mammals doing well in Britain (although they number just 3,700). A fifth of the country’s wild mammals are at high risk of extinction, research shows. (Photo by Maurice Flynn/The Mammal Society)