Second, close to the skull were three roughly basketball-sized boulders that shouldn’t have been there. The site consists of fine layers of sediment that were probably the mucky bed of a pond. There were no other rocks around or signs that a fast-flowing current could have deposited the boulders from elsewhere. Moreover, Fisher has seen similar finds before at other mastodon and mammoth kill sites in the upper Midwest and has a theory to explain them: they were the equivalent of Ice Age meat lockers. If hunters were fortunate to bring down a mammoth, they would have a bounty of meat on their hands but faced the problem of saving it from spoilage and the unwelcome attentions of scavengers and predators. The solution was stashing carcasses at the bottom of a pond, weighed down by boulders that were probably lashed together with ropes made of hide or plant fiber.