"an unlikely Pandora"
'Pandora' by Lefebvre (1882)
Public Domain'Pandora' by Lefebvre (1882) - Credit: Jules Joseph Lefebvre
Pandora, in Greek mythology, was the first woman.

Out of curiosity, she is said to have opened a jar (often wrongly translated as a box) which led to all the evils of the world being released.

Metaphorically speaking, then, to open Pandora's box is to start something that will lead to innumerable troubles; the equivalent of opening a can of worms.