Glaciers and ice sheets in areas such as Arctic and Atlantic regions with sub-zero temperatures have proved to have thriving populations of microorganisms. These microbes are found within the cold winter snowpack and in small cylindrical melt pools on the surface of glaciers or as a biofilm. Microbes are also found within meltwaters, bursting out under pressure from beneath glaciers, where they thrive despite the extreme temperatures and pressures. These microbes influence nutrient cycling by feeding on nutrients and organic matter washed in from the surface of the glacier. Glacier microorganisms can help biologists to understand biochemical cycling and how nutrients are transferred to neighboring freshwater and marine ecosystems.