One of nature’s most dramatic mysteries—the migration of birds, turtle, salmon and other animals—depends on iron magnets. The bodies of some animals contain minute deposits of magnetite that are sensory navigators. Far reaching in scope, Iron, Nature’s Universal Element also looks at global issues including iron’s power over the earth’s oceans, vegetation, and populations; and the low-protein diets that lead to long-term cognitive damage in iron-deficient children in poor countries.