Nur-Ab-Sal was an Atlantean god-king in Indiana Jones and the Fate of Atlantis. He also owned a necklace which seemingly he possessed with his consciousness.
The necklace was found in Iceland during the Jastro Expedition and worn by Sophia Hapgood ever since. Hapgood claimed she had psychic powers and was perhaps Nur-Ab-Sal's influence driving her.
When Sophia reached the second circle of Atlantis, he gained control over her and revealed the true intentions: to be the king of Atlantis through Sophia. But Indiana Jones threw the medallion violently in a lava pit freeing her from his influence.