Whale meat and blubber are Faroese delicacies. Nansen and Johansen survived on walrus and polar bear meat and blubber. Whale oil was obtained by boiling strips of blubber harvested from whales. Whale oil is oil obtained from the blubber of whales. Also widely used were animal fats (butter, fish oil, shark liver, whale blubber, seals). All whales have a thick layer of blubber. Sperm oil has a different composition from common whale oil, obtained from rendered blubber. Whaling is a method of hunting whales for their meat, oil and blubber. Walruses maintain such a high body weight because of the blubber stored underneath their skin. Whale oil was the result of "trying-out" whale blubber by heating in water. Whale blubber, which tastes like arrowroot biscuits, has similar properties. It was primarily hunted for its blubber, oil, and baleen. All porpoises have a thick layer of blubber. They kill their prey with their long tusks and eat their blubber and skin. Elephant seals are shielded from extreme cold more by their blubber than by fur.