The scuba-diving philosopher and bestselling author of Other Minds explores the origins of animal consciousness. Dip below the ocean's surface and you are soon confronted by forms of life that could not seem more foreign to our own: sea sponges, soft corals and flower-like worms, whose rooted bodies and intricate geometry are more reminiscent of plant life than anything recognisably animal. Yet these creatures are our cousins. A Times and Sunday Times Book of the Year.