21. Crystal Skull Daniel finds a glowing crystal skull inside a Mayan pyramid that was first discovered by his grandfather decades before. When Daniel goes to investigate, a mysterious force makes him disappear and the SG-1 team must find his grandfather to unlock the mystery of the skull and save his life. 22. Nemesis O'Neill is kidnapped and taken aboard a ship by the Asgard. The ship is full of small, metallic, bug-like creatures called replicators on a mission to destroy Earth. O'Neill plans to blow up the ship and sacrifice himself, but can the Stargate team find another way to stop this apocalyptic scheme?