world of mini-microbes discovered deep under ice in Greenland reveals apparent survival skills that could come in handy on Mars or other extreme worlds: Get small and hang in there. The tiny creatures are smaller than most commonly known bacteria and have endured at least 120,000 years in subzero temperatures, crushing pressure, low oxygen levels and almost no nutrients. They were found in ice core samples taken nearly 2 miles (3,000 meters) below a glacier. Researchers said they could be a million years old.