Consortia of archaea and bacteria are abundant in Nature. ~ German marine biologist Antje Boetius
The remains of marine life make their way to the ocean floor as dissolved organic matter (DOM), the deposit of marine snow. The dead biomass decays in subsurface sediments, producing methane which rises to the seafloor.
Before reaching the water column, the methane is consumed by consortia of methanogenic archaea and bacteria which may form voluminous mats on the ocean floor. These microbes work together to make a meal.
Archaea intake methane (CH4) and oxidize it to carbonate (H2CO3). The reaction continues as the archaea pass energy to partner bacteria through pili, which are connective tubes that the bacteria provide. Using readily-available sulfate (SO42–), the bacteria reduce the carbonate and respire hydrogen sulfide (H2S).