Hesiod's original Pandora story describes a jar instead of a box.
In Works and Days, Pandora receives a large storage vessel commonly identified by the Greek word pithos. A pithos was a substantial ceramic container used in the ancient Mediterranean for storing commodities such as grain, oil, or wine.
The familiar phrase “Pandora's box” became established through a later translation tradition. The sixteenth-century humanist Desiderius Erasmus translated the Greek vessel using the Latin word pyxis, meaning box or small container, helping create the modern expression.
The distinction matters because the wording reflects transmission history rather than the earliest version of the myth. Modern paintings, books, and films usually keep the box because it is now the universally recognized form.