In Greek mythology, the jar Pandora opened is called a pithos. A pithos was a large ancient Greek storage vessel, typically used for commodities such as grain, oil, or wine.
The word “box” became standard through later translations and retellings. The Latin writer Erasmus helped popularize the misleading box image when he rendered the Greek vessel as a small container in a sixteenth-century version of the proverb.
This detail matters because a pithos is much larger and more practical than the compact box shown in modern illustrations. The myth’s original imagery therefore involved a substantial storage jar rather than a decorated gift box. “Pandora’s box” remains the established expression in English despite that translation history.