In Hesiod’s Works and Days, Pandora receives a jar rather than a modern box.
The Greek word used in the poem is pithos, a large earthenware storage jar. Such jars were used in the ancient Mediterranean for commodities including grain, oil, and wine. The vessel in the myth is therefore better imagined as a substantial container than as a small hinged box.
The familiar phrase “Pandora’s box” developed through later translation history. The Renaissance humanist Erasmus translated the Greek term into the Latin pyxis, meaning box, and that wording strongly influenced later European languages and popular culture.
The jar-versus-box distinction does not change the central plot: the container holds forces or troubles that escape into the world when Pandora opens it. Modern retellings often retain “box” because it is the established expression.