Flexible Glass

Flexible is a legendary lost technology that was supposedly presented to Roman Emperor Tiberious Caesar (between 14–37 AD). As recounted by Isadore of Seville, the craftsman who invented the technique brought before Caesar a drinking bowl made of flexible glass, and Caesar threw it to the floor, whereupon the material dented, rather than shattering. He was then able to repair the dent with a small hammer. Upon telling Caesar that he alone knew the technique of manufacture, Caesar had the man beheaded, so his new invention didn’t undermine the value of Gold and Silver.