A grizzly bear at the Minnesota Zoo put on a show for visitors Monday, using two paws to smash a rock against its enclosure glass repeatedly until the pane shattered. It stayed in place “like a windshield,” but the exhibit will be closed until it is repaired. The full cost of a permanent glass repair could be in the tens of thousands of dollars. Zoo staff said they don’t even know which of the enclosure’s bears is the guilty party. Their money, though, is on Kenai—a male who will weigh 800 to 900 pounds when fully grown.