A Prince Rupert’s Drop is formed when molten glass is dropped into cold water. The glass rapidly cools into the shape of a tadpole. This results in the outer surface of the drop solidifying while the inside remains molten. When the inside begins to cool, it contracts the outer surface. This process creates a very strong structure.
The tail is the weakest point of the drop as it is too thin to have layers. If broken, the entire drop will shatter upon impact. So, how does this piece of glass fare when struck by a speeding bullet?