PERTH, WESTERN AUSTRALIA—Students from the University of Western Australia have uncovered a spearhead made of bright green glass on Rottnest Island, according to a report from ABC News. Nearly 4,000 Aboriginal men and boys were imprisoned on the island, also known as Wadjemup, between 1838 and 1931. The prisoners are thought to have made such spearheads from scrap pieces of glass for use in trade, building relationships, and for hunting small nocturnal marsupials called quokkas. The spearhead, which has been estimated to be at least 100 years old, has been reburied on the island. For more on archaeology in Australia, go to “Alone, but Closely Watched.”