The balls are antimicrobial, meaning they kill 99 percent of germs, according to Emma Filar, who works at the museum.

Marketing and communications manager Emma Filar said that the museum anticipates a robust lost and found — and a windfall in loose change.

According to Prof. Skeat it is derived from the Span. filigrana, from “filar, to spin, and grano, the grain or principal fibre of the material.”