The Cup of Ankh is a cup that if someone drinks the Elixier of Life from it, they will become a God and become immortal. This was a major part of the mystery in Season 1. Many people were after it.
There was a myth that Amneris had hid the Cup. Anubis found out and broke it into 7 pieces, and said,"Every 25 years, on a certian hour, on a certian day, someone willl be given the chance to put it together," thus, creating the 7 'puzzle pieces'.