In the Fifth Element, in 1914 the Mondoshawans collect the stones and the Fifth Element from the chamber of the elements.
As they are leaving, Luke Perry shoots their leader, leading to it being trapped in the chamber. It is only able to pass the key to the human priest.
300 years later, evil returns. When Bruce Willis and company go to the chamber to activate the five elements and defeat the evil.
But when they open the door, there is no sign of the trapped Mondoshawan. It was wearing metal armour (or was a being made of metal), so there should still at least be a husk.
What happened to the trapped Mondoshawan leader?