In recent weeks, headlines have captured public imagination with the tantalizing phrase: “Dinosaur eggs found on Mars.” NASA’s Curiosity rover, tirelessly exploring the slopes of Mount Sharp in Gale Crater, recently imaged a set of rounded, clustered rock formations that immediately drew attention. To the untrained eye, the resemblancance to a clutch of fossilized eggs is uncanny, leading many popular outlets to jump on the “dinosaur egg” metaphor. Yet planetary scientists are clear: these are not biological fossils, but rather natural geological features formed by mineral deposition and erosion in fractured rocks. Still, behind the hyperbole lies something truly significant.

These unusual formations ~ nicknamed “egg-like rocks” in the rover’s logs ~ are more than curiosities. They represent evidence of complex geological and hydrological activity in Mars’ past. In fact, they may record episodes when water, heat, and chemical interactions altered the crust, leaving behind structures that incidentally resemble the eggs of long-extinct reptiles. And it is this watery, active Mars of the past that fuels one of the most profound scientific questions of our time: did life ever evolve on Mars? To answer that, scientists turn back the Martian clock. About 4.1 to 3.7 billion years ago, during the Noachian epoch, Mars was very different from the cold desert we see today. Geological evidence shows extensive river valleys, deltas, and possible shallow seas. The planet’s atmosphere was thicker, temperatures could occasionally rise above freezing, and liquid water was stable on the surface.

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If Earth’s microbial life emerged around the same time, could Mars have been home to microbes too? The idea is........

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