The newly reported animals complete their life cycle in the total absence of light and oxygen, and they are less than a millimetre in size. They were collected from the deep basin where they live in a nearly salt-saturated brine. This brine, because of its density, does not mix with the waters above. As a result, the brine is completely anoxic, and high in ammonia. Also, due to the action of sulphate reducers, it contains sulphide at a high concentration. In the brine, the abundance of cells is not high. Extremophiles predominate, including members of the deep-sea hydrothermal vent community of archaea and bacteria. Eukaryotes are also found in l'Atalante, including ciliates (45%), dinoflagellates (21%) and choanoflagellata (10%).