6Carbon. It's in the fibers in your hair, the timbers in your walls, the food that you eat, and the air that you breathe. It's worth billions of dollars as a luxury and half a trillion as a necessity, but there are still mysteries about the element that can be both diamond and coal. Where does it come from, what does it do, and why, above all, does life need it? With poetic storytelling, Robert M. Hazen leads us on a global journey through the origin and evolution of life's most essential and ubiquitous element.