Maybe we should all take another look at the movie Planet of The Apes. Visitors to a Zoo in China photographed a capuchin monkey sharpening a rock and then later use it to shatter its glass enclosure.
The monkey was frightened by what it had to done and ran from the enclosure but later went back to see admire his vandalism by touching the glass.
The zoo’s staff said this specific capuchin is unlike the others; this one can use stones to break walnuts to eat while others just use their mouths to break the walnuts open. The zoo has said that they have cleared off any stones and rocks from the enclosure just to be safe.