Spear

The spear was one of the keys to the heart of Ubar. It had notches on it, 69 times and it had a heart symbol, symbolizing the heart of the city. Normally, a town's heart is the well of water that provided water to a town. The spear was in a museum when it was found and it served as a key to the location as Safia correclty guess it was the well in the center of the ruined chamber that lead to the heart of Ubar.