Flexible glass is an interesting subset of structural glass systems, as it is a form of glass technology that is strong because it uses a philosophy of bending but not breaking.

Bendable glass technology allows for more elaborate shapes and even functionality such as that seen with foldable smartphones. Its most common use, however, is in fibre optics, where it allows light to pass through even if bent in a coil, and can survive strikes from a hammer.

However, this fascinating form of glass was, if the legends are to be believed, invented over 2000 years ago, during the Roman Empire, but quickly became a lost technology for a truly bizarre reason.

The man who created what was known in Latin as “vitrum flexile” is unknown, but after proving he could make glass that would dent rather than break under impact, he was granted an audience with Emperor Tiberius.

The drinking bowl was dented, but careful repairs with a hammer worked it back into shape. By the accounts of historians Pliny the Elder and Petronius, those in attendance were impressed.

Tiberius, however, simply asked if this inventor was the only person alive who knew how to make glass this way. Once the inventor swore he was, he was promptly beheaded, taking his secrets swiftly to the grave with him.

According to Petronius’ account, the reason why he did this was that Tiberius was scared that if this glass were to become widely available, it would be more valuable than gold and silver, the main precious metals used for currency in Rome.

There are questions about whether this story happened, with Pliny the Elder having his doubts and Petronius being primarily known as a satirist. Regardless, it would take nearly two millennia for a bendable glass of any kind to be created after this, unless another invention was also lost.