Emiliania huxleyi has more going for it than just a beautiful name. Despite being only a few millionths of a millimeter in size — about a tenth of the thickness of a human hair — this unicellular alga has a major impact on our planet. Blooms of E. huxleyi, which can cover more than 100,000 square kilometres of ocean, are visible from space and affect the global climate; the concerted impact of all the cells in the bloom influences carbon and sulphur cycles and even changes how much light the Earth reflects. Under an electron microscope, E. huxleyi cells reveal their striking, alien beauty; encased in tiny plates called coccoliths, they look like strange spaceships or escape pods. E. huxleyi lives throughout the world’s oceans, from the warm tropics to the subarctic seas, and these plates underlie its remarkable impact on the planet’s climate and geology.