A teardrop shaped glass bead with a tail, this astonishing object delighted Europeans in the 17th century. Popularized in England by Prince Rupert who gave a few of them to Charles II in 1660, these drops are made by immersing molten glass in cold water. The outside of the glass quickly forms a shell that incases the pressure of the still-expanding molten glass within. Once the entirety has cooled, the glass shell is holding back enormous pressure and the bead can easily withstand hammer-blows. However, there is a glass tail to the drop, that when broken, releases all the energy, immediately reducing the drop to a fine, glass powder.