The Christmas Island shrew (Crocidura trichura), once abundant on Christmas Island, has been declared extinct due to the introduction of invasive species and habitat destruction. Despite brief rediscoveries in 1958 and 1984, the species could not be saved, highlighting the fragility of ecosystems and the impact of human activities on native wildlife. Its extinction marks the 39th mammal species lost in Australia since colonization, serving as a reminder of the unseen losses in biodiversity.