In Hesiod’s Greek myth, Pandora opened a jar rather than a modern box.
The relevant Greek word is pithos, a large earthenware storage jar used for liquids or goods. Hesiod’s Works and Days describes Pandora removing the lid, after which troubles spread among humanity. The vessel was therefore a substantial household container, not necessarily a small wooden box.
The familiar phrase “Pandora’s box” developed through a Renaissance-era translation associated with Erasmus. That wording became dominant in European languages and later popular culture. Because of this translation history, illustrations usually show a box even though the earliest literary source describes a jar.