There was never a “Eureka!” moment for David McKay. Instead, a slow, gradual process that led to the announcement that fossilized minerals produced by bacteria may lie deep inside a 4-billion-year-old potato-sized Martian meteorite found in Antarctica in 1984. It was one of the first pieces of credible evidence that remnants of life, however tiny, may have come from Mars to Earth. That was five years ago. Afterward, scientists still debated whether the fossils truly were of non-Earth origin.
