A Pair of 19th Century walrus tusks from Herschel Island, part of the Canadian Yukon. They were the property of William Mogg, who spent 2 winters there in 1889-92. Walrus ivory is a valuable material that comes from the modified upper canines of walruses and is also known as morse. It has been used for centuries to make luxury items, such as chess sets, crucifixes, and other carvings. In cross-section, walrus ivory has a marbled core surrounded by a creamy white dentine layer. Walrus ivory was a popular commodity in medieval Europe, and its use peaked in the 12th century. The Norse established settlements in Greenland and Iceland and supplied ivory to Europe. The initial exploration and settlement of Greenland around 980-990 CE is thought to have been motivated by the hunt for ivory. Over-hunting of walruses contributed to the collapse of Norse Greenland. Whitby Museum.