This localization appears only in some expeditions, which advertise its presence with rumors in the world map screen.
There may be one to three golden seals per level. Additionally, they will spawn at random accross the entire map, making the journey more difficult. All Golden Seal locations are revealed once the Pyramid is discovered. It is necessary to activate all of them to unearth the buried golden pyramid. If it isn't done, it will be impossible to finish the expedition normally.