Did flexible glass, so strong that a dent could be knocked out with a hammer, exist in first-century Rome? Probably not  —  but its stories do hold a small, intriguing place in ancient folklore.

While several legends offer conflicting tales, they all paint a picture of a glass formula so remarkable that it threatened to upset an entire Roman economy based on copper, silver, and gold. In fact, as one story goes, the highly prized material caused one unfortunate glassmaker to lose his head.

Read more from the Corning Museum of Glass.