Deep-sea bacteria, artwork. The main image shows the sea floor spreading (arrows) either side of a mid-ocean ridge as rising magma (orange) forms new rock. The inset (upper left) shows microbial mats (coloured domes and threads) of bacteria sustained by chemical reactions with the basalt rock itself. Previously it was thought that only shallow sea floors and hydrothermal vents were capable of supporting life, but now it is thought that the rocks of the deep sea floor are also capable of supporting large amounts of microbial life. It is thought that the the deep sea floors may rival other locations in the amount and diversity of microbes supported.