Neanderthals collected seashells by the seashore. They also may have swum underwater to retrieve live clams to later shape into sharp tools and scrapers, according to a new study.

“Our findings enlarge our knowledge of the range of capacities Neanderthals had,” said Sylvain Soriano, an archaeologist from Paris Nanterre University and an author of the paper. “Now we can say that they were able to dive in shallow water.”

The conclusion is based on more than 170 handmade shell tools found in an Italian cave. The finding provides insight into how Neanderthals, who hunted deer with flint-tipped spears and used fire to produce birch tar, took advantage of their aquatic resources to fit their needs and fill their utility belts. The paper was published Wednesday in the journal PLOS One.

Researchers uncovered Grotta dei Moscerini on the western coast of Italy at the base of a limestone cliff in the late 1930s. During an excavation in 1949, archaeologists using mesh sieves dug up dozens of seashells. The cave’s Neanderthal inhabitants had sharpened or modified many of the shells into thin cutting tools, similar to how they had chipped flint into stone blades. Some of the shell tools dated back to around 100,000 years ago.