Walrus attacks are attacks inflicted upon humans, other walruses and other animals by the walrus. Like walrus ivory, sperm whale ivory has two distinct layers. They subsisted by hunting walrus and whale and by fishing. There is some evidence of either whale or walrus ivory used by the ancient Irish. Killer whales are believed to assist their hunters in driving walrus. During the Second World War Saro manufactured Supermarine Walrus and Supermarine Sea Otters. It is also an occasional prey of the walrus and Arctic fox. The tusks of a Pacific walrus may attain a length of one meter. Certain antelopes, the musk-deer, camel, horse, boar, various apes, seals, and the walrus, offer instances. These include a termite, a pumpkin, a honey bee, a walrus, and a crocodile. The island was also a habitat for the Atlantic walrus until the mid-16th century. One nest was found in the skull of a walrus. A chimney was improvised using snow and walrus bones. Male Atlantic walrus weigh an average of . "I Am the Walrus", which The Beatles were recording that evening.