Scientists find amazing 5,000-year-old crystal dagger in Spain This mythical looking dagger may have played a symbolic role in prehistoric Iberian society. Miguel Angel Blanco de la Rubia. Inside an ancient tomb near Seville, researchers found the remains of several individuals buried in a ritualistic fashion, as well as a most striking artifact: a quite beautiful dagger made from rock crystal. The intricately carved crystal dagger has been dated to at least 3000 BCE, making it the “most technically sophisticated and esthetically impressive collection of rock crystal material culture ever found in Prehistoric Iberia,” according to Spanish researchers who investigated the site.