Past life on Mars? 'Leopard-spot' rocks could be biggest clue yet

Unusual rocks discovered on Mars by NASA's Perseverance Rover feature distinctive "leopard spots" that could be the strongest evidence yet of ancient microbial life. The 3.5-billion-year-old mudstones contain minerals likely formed through chemical reactions between mud and organic matter - reactions typically driven by microbes on Earth. While scientists haven't confirmed biological origin and non-biological processes remain possible, these "potential biosignatures" represent the most compelling evidence found, highlighting the critical importance of returning these samples to Earth for definitive analysis.