[SunkenCiv]

[snip] Apparently, a form of flexible glass existed during the reign of the Roman Emperor Tiberius Caesar. So the story goes, as told by Petronius, a glassmaker brought a drinking bowl made of the material before the Emperor.

According to historical accounts, when the bowl was tested for its strength, it dented rather than shattered. What's more, the inventor swore he was the only person who knew how this miracle was achieved.

Tiberius had the man executed, fearing that the glass would devalue gold and silver because it might be more valuable. [/snip]

I've got to hold an ice pack on my head for a while, I bumped it when I fell off the chair laughing.

[Red Badger]

he was from Wakanda......................

[Grimmy]

We all know how that dude got that “glass” bowl.

Outerspace aliens from outer space gave it to him as a parting gift after the probing party.

[AdmSmith]

Since the main patents are no longer valid...

Patents related to aluminium oxynitride include:

Aluminium oxynitride having improved optical characteristics and method of manufacture TM Hartnett, RL Gentilman U.S. Patent 4,481,300, 1984
Process for producing polycrystalline cubic aluminium oxynitride JW McCauley U.S. Patent 4,241,000, 1980
Transparent aluminium oxynitride and method of manufacture RL Gentilman, EA Maguire U.S. Patent 4,520,116, 1985; U.S. Patent 4,720,362, 1988
Transparent aluminium oxynitride-based ceramic article JP Mathers U.S. Patent 5,231,062, 1993

https://en.wikipedia.org/wiki/Aluminium_oxynitride

...it is the production process that is expensive: https://www.azom.com/article.aspx?ArticleID=8095

Let's assume that we wouldn't build a small aquarium out of Alon, but instead let's deal with a standard large aquarium size of 180 gallons. A typical 180 has dimensions of 72 inches long, 24 inches high and 24 inches wide – this means we need three panes that are 5,184 square inches combined and two end panes that are 1,152 square inches total. Since Alon has an average price of $10 to $15 per square inch, the total cost of the Aluminum Aquarium would be $63,360 to $95,040 for the aluminum ‘glass’ alone!

https://reefbuilders.com/2019/05/02/transparent-aluminum/