A clever capuchin monkey in a zoo in the Chinese Henan province has stunned the world with its ingenious plan to stage a zoo-break. The intelligent primate reportedly spent hours sharpening a stone he found in his enclosure before striking the glass viewing pane of its enclosure till it cracked and almost gave way.

The sudden sound of glass shattering scared the monkey who ran away, while astonished visitors alerted authorities.

According to Metro UK, Tian Shuliao, a staff member of the Zhengzhou Zoo, told the local media, “This monkey is unlike other monkeys. This one knows how to use tools to break walnuts. When we feed walnuts to other monkeys, they only know to bite it. But it had never hit the glass before. This is the first time. It’s toughened glass, so it would never have got out. After it happened, we picked up all the rocks and took away all its ‘weapons’.”