For millions of years shells made of calcium carbonate were all the rage amongst marine life, then a new plucky family known as vertebrates turned marine fashion inside-out by putting skeletons on the inside.
Fritz Haber was a German chemist, who made food from air. He invented the Haber-Bosch process that takes nitrogen from the air and turns it into fertiliser, feeding billions - half the protein in our body is a result of this process. He won a Nobel prize and was Albert Einsteins friend and for a time was one of Germany's heros. However he was also one of the fathers of gas warfare, responsible for countless horrific deaths (including his wife) and is considered a war criminal today.