3 pages, 1 figure[EN] Wherever you look there is life that you cannot see. On your hands, your table, your computer, the floor, the grass, the air and the water. Microbes thrive in all kinds of habitats, including our own body, and despite their insignificant size, they are responsible for biogeochemical processes of global importance. The ocean is no exception, as most marine life is actually microbial, and seawater is essentially a soup of drifting microorganisms. Among these, the tiniest living beings are bacteria and archaea. With around 1029 estimated cells in the ocean (more than stars in the universe), and 1010 different species, both the chemistry and the life in the ocean are largely controlled by microbial activity and their inter...