"Rare marine coral fossils have been found in the Narmada valley for the first time," said Vishal Verma, head of Mangal Panchayatan Parishad, an archaeological research group.
"We estimate that it is nine crore years old, giving currency to the notion that Tethys ocean (which existed between the continents of Gondwana and Laurasia during the Mesozoic era) extended to this region," he said.