Between 20 million and 4 million years ago, a massive species of shark ruled Earth’s oceans. Otodus megalodon could grow to 18 meters (59 feet) long—as long as a bowling lane. The babies were the size of great white sharks, about 3.5 m (11 ft) long! Recently, scientists from the University of Valencia in Spain made a big discovery about megalodon’s not-so-tiny offspring.

The researchers studied fossils of preserved megalodon teeth from nine locations around the world. Five of the sites had high numbers of teeth from juvenile sharks. The scientists realized that these areas likely served as nurseries, shallow waters where baby sharks would live until they were big enough to survive in the open ocean.