In Hesiod’s original account, Pandora opened a jar rather than a box.
The Greek word used in the myth is pithos, a large container commonly used in the ancient world for storing commodities such as grain, oil, or wine. Hesiod’s Works and Days says that Pandora opened the container and released the evils kept inside it.
The “box” version became standard in many later retellings because of a sixteenth-century Latin translation by the humanist Erasmus. Erasmus translated the Greek container as a box, and that wording became much more influential in European languages than the original description of a jar.
This difference is one of the most common details people get wrong about the myth. The title “Pandora’s box” is now firmly established in English, but “Pandora’s jar” is closer to Hesiod’s Greek text.