Hesiod said Pandora opened a pithos, a large storage jar, rather than a modern box.
In Works and Days, Hesiod uses the Greek word pithos for the container that holds the troubles released into the world. A pithos was a substantial ceramic vessel used in ancient Greece and elsewhere around the eastern Mediterranean for storing commodities such as grain, oil, or wine. It could be large enough to stand on the floor and was not shaped like a small hinged box.
The familiar expression “Pandora’s box” developed through translation history. The sixteenth-century humanist Erasmus translated the Greek vessel term into the Latin word pyxis, meaning a box or small container. That choice helped establish the wording that became standard in European languages, even though “jar” is closer to Hesiod’s original object.
Ancient versions also differ in details about the container and what remained inside it. The important textual point is stable: the earliest surviving account describes a storage jar, while the box belongs to later reception and translation.