Hesiod’s original Pandora myth describes a jar rather than a box.
In Works and Days, the Greek word is pithos, meaning a large storage jar or earthenware vessel. Such jars were used in the ancient Mediterranean for goods including grain, oil, and wine. Pandora opens this container, releasing the troubles that had previously been kept away from human life.
The familiar phrase “Pandora’s box” developed later through translation history. The Renaissance humanist Erasmus translated the Greek vessel as a Latin pyxis, a small box, in a version of the story. That choice helped establish the expression used in English and many other languages.
The jar detail is not a minor artistic variation: it is part of the earliest surviving literary account. Paintings, books, cartoons, and films commonly use a decorative box because that is the established modern image. In strict mythological terms, however, “Pandora’s jar” is closer to Hesiod’s wording.