In Greek mythology, a pithos was the type of ancient Greek storage jar associated with Pandora’s troubles. Hesiod uses the Greek word pithos, not the word for a small box.
A pithos was a large earthenware container used to store commodities such as grain, wine, or oil. These jars could be tall and substantial, making them a better match for the ancient description than the compact box shown in many modern illustrations. The famous English phrase developed because early translators rendered the container as “box.”
The translation became so influential that “Pandora’s box” is now the standard expression in English. The source myth itself is more accurately described as the story of Pandora’s jar. Amphorae, kraters, and hydriai were also Greek pottery forms, but they served different shapes and functions and are not the container named in Hesiod’s account.