Skulls made from crystal and gems are among the most astonishing artefacts ever discovered. They seem surprisingly modern and naturalistic. Little is known of their origins, the methods with which they were made, and their age. “E.T” stands in the centre - a bizarre head from smoke quartz which was discovered in Guatemala in 1908. Scientists have proven that it is at least 500 years old. It was precisely worked by manual grinding and polishing.