P7X-377 has an enormous Mayan pyramid that stands over 1000 meters high. Its cavernous interior has unusually high, potentially lethal levels of muon radiation, and the indication of leptons suggests that some material inside is slowing down neutrinos, which ordinarily pass through matter. The pyramid contains a single artifact, a crystal skull resting on a pedestal at the end of a long elevated causeway. The skull is capable of creating an energy field that teleports one to see the native giant aliens of Quetzalcoatl's race. Daniel's grandfather, Nicholas Ballard, remained behind on the planet in a cultural exchange of knowledge with the aliens.
Episode Reference: Crystal Skull