This Rare, Ancient Crystal Dagger Reminds Us of DUNE Twitter Dune is to make a statement. Fremen craft the dangerous weapons from the teeth of dead sandworms. And if one draws the sacred weapon, they cannot resheath it until it draws blood. All of that came to mind when we learned about the discovery of a 5,000 year old crystal dagger in Spain from The Daily Mail. Detailed in a published study from the Quaternary International in 2015, the eight-and-a-half-inch dagger was found in a tomb at the Tholos de Montelirio site. The dagger in and of itself isn’t unusual, but what’s it’s crafted from sets it apart: rock crystal.