Platypus - The platypus does not have a true beak like a bird, because the bill is actually quite soft and spongy and is covered with a highly sensitive skin. The fur was even more revealing. Hair and fur are features for a mammal, like feathers for birds. It was therefore evident that this mysterious animal had to belong to the large group that contain such unlikely creatures as shrew-mouses, lions, elephants, and man. The fur of a mammal is meant to isolate it so that the body can maintain a high and equal temperature. Because of this, the new animal had to be equally warm.