Tortoises’ thick shells protect them from most predators. But our closest relatives have found a way to circumvent this defense: vigorously bashing them against trees.

In a paper published today in the journal Scientific Reports, scientists report seven chimpanzees breaking open forest hinge-back tortoises in Gabon’s Loango National Park. The behavior occurred on multiple occasions over 5,000 hours of observation, and the primates often shared the meat with others in their group.

This is the first time than any chimpanzee has been documented eating any kind of reptile. It’s also unique because the way in which the primates eat these tortoises—slamming them against tree branches and trunks—is a type of “percussive” technology that is akin to tool