Bacteria Bacteria are the most successful organisms on Earth. The earliest found fossils of bacteria date back to 3.5 billion years ago. This makes them the oldest group of organisms. Today bacteria can be found in anything, even in the hardest living conditions. Bacteria can live 1,200 ft. under the ice in Antarctica and some can even live in volcanic vents near deep-sea level, where temperatures reach near 360 degrees. They have also been found living miles under the earths surface. Bacteria are found in large numbers. About 2.5 billion bacteria are captained in one gram of rich soil. Bacteria can only be seen with a microscope because they are