Researchers have found signs of microbial life at least 3.5 billion years old in a carbon-bearing chert from Bhitardari in the Singhbhum Craton, which spans parts of Jharkhand and Odisha. Four of the eight zircon crystals studied gave an age of about 3,497 million years, fixing the rock’s age. Carbon isotope patterns and degraded organic matter show the carbon came from living organisms. The researchers say it may be the oldest directly dated rock with a confirmed biosignature, suggesting microbes existed roughly 1 billion years after Earth formed.