In Greek mythology, Pandora’s troubles were held in a jar. The original Greek story describes a large storage vessel called a pithos, not a small hinged box.
Hesiod’s Works and Days says the vessel contained evils that spread among humanity after it was opened. The word “box” became attached to the story much later through a Latin translation and retelling.
A pithos was a substantial Greek container, commonly used for storing goods such as grain, oil, or wine. Its size and practical purpose make it different from the decorative boxes shown in many modern illustrations.
The familiar phrase “Pandora’s box” remains the standard expression in English, even though “Pandora’s jar” is closer to the ancient Greek wording. The mistranslation is one of the story’s most famous historical changes.