It's easy to think of science as clear, clean and linear - the progressive accumulation of information driving a steady increase in our understanding of the world. But, in truth, it's messy. There are fits and starts. Bafflement. Wrong turns. Dead ends. Head-scratching questions that defy answers. There are also a lot of happy accidents, often made by people not even in science - as the workers on an oil and gas rig off the coast of Angola discovered in August of 2015.