A crystal skull is a stone carving in the shape of a human skull. The sculptures vary in size from a few inches to life-size. Some are made of pure quartz crystal, but many are made of other types of stone found in abundance on Earth. Some stone skulls are genuine artifacts from Mesoamerican cultures such as the Aztecs and are known as skull masks or death heads. But the crystal skulls that interest New Agers are extraterrestrial in origin or come from Atlantis. They allegedly are endowed with magical powers such as the spontaneous production of holographic images and the emission of weird sounds. Today, millions of skulls, made of various types of stones and metals, are manufactured in a variety of sizes for the New Age paratrinket market, as well as for the museum replica market. And, despite the fact that replicas are easily made and are available from a variety of sources, advocates of the paranormal nature of crystal skulls like Nick Nocerino claim that no one knows how these skulls were made and that they are impossible to duplicate. Nocerino is the founder of the The Society of Crystal Skulls, International. His society uses psychometry, remote viewing, and scrying as part of their research methodology. 

The myth of crystal skulls as extraterrestrial and extra-powerful seems to have begun with F. A. "Mike" Mitchell-Hedges (1882-1959) and his adopted daughter Anna. Their creative fictions have been uncritically promoted by Frank Dorland, author of Crystal Healing: The Next Step, and Richard Garvin, author of The Crystal Skull: the Story of the Mystery, Myth and Magic of the Mitchell-Hedges Crystal Skull Discovered in a Lost Mayan City During a Search for Atlantis (1973). The myth has been carried on by Ellie Crystal, who likens the quest for crystal skulls to the quest for the Holy Grail, and Josh Shapiro, co-author (with Nocerino and Sandra Bowen) of Mysteries of the Crystal Skulls Revealed.