What sort of object can shrug off a bullet, but shatters with just a little touch? The answer is a Prince Rupert’s Drop, an object formed from molten glass simply dropped into water to cool.
The Prince Rupert’s drop is a strange artifact that results from the way that a drop of molten glass cools in water. When the liquid glass hits the surface of the water, the outside material immediately begins to cool and harden into a solid, which creates the solid shape of the drop. However, because of this, the interior of the drop takes much longer to cool, and, confined by the already-solid shape of the drop, creates a tremendous amount of tension as the interior material shrinks and cools into a solid. This results in a bulb that has incredible inter-molecular forces and therefore great strength, but which exists in an unstable configuration. If even one link in the chain is broken, such as at the vulnerable tail end, the entire drop will explode into tiny pieces.
For more on Prince Rupert Drops, you can check out Destin’s earlier video on the subject, embedded below:
You can also see even more footage of Prince Rupert’s Drops from Smarter Every Day on his second channel: