The occurrence of a wide variety of metal-carbon bonds in living organisms, ranging from bacteria to humans, is only recently recognized. Of course, the historical examples are the B12 coenzymes containing cobalt-carbon bonds, but now such bonds are also known for nickel, iron, copper, and other transition metal ions. There is no other comparable book; MILS-6, written by 17 experts, summarizes the most recent insights into this fascinating topic.