In classical Greek mythology, Pandora was the first woman on Earth. Zeus ordered Hephaestus, the god of craftsmanship, to create her, so he didusing water and Earth.[4] The gods endowed her with many gifts: Athena clothed her, Aphrodite gave her beauty, and Hermes gave her speech.[5]
When Prometheus stole fire from heaven, Zeus took vengeance by presenting Pandora to Epimetheus, Prometheus' brother. With her, Pandora was given a beautiful container which she was not to open under any circumstance. Impelled by her curiosity given to her by the gods, Pandora opened it, and all evil contained therein escaped and spread over the earth.

Pandora's box is an artifact in Greek mythology, taken from the myth of Pandora's creation in Hesiod's Works and Days. The "box" was actually a large jar given to Pandora which contained all the evils of the world.

Today, the phrase "to open Pandora's box" means to perform an action that may seem small or innocuous, but that turns out to have severe and far-reaching consequences

It's said to be a container treasuring all the evils of the world...!

Where any thing can come out od it - UNEXPECTEDLY

Pandora's box is an artifact in Greek mythology, taken from the myth of Pandora's creation in Hesiod's Works and Days. The "box" was actually a large jar given to Pandora ("all-gifted", "all-giving"), which contained all the evils of the world.

Today, the phrase "to open Pandora's box" means to perform an action that may seem small or innocuous, but that turns out to have severe and far-reaching consequences

Source: google search