Crystal

A Crystal is a piece of technology, which could refer to:
 * 1) Ancient crystal power cell, power sources created by the Lanteans.
 * 2) Control crystal, crystals used in controlling the technology of a variety of cultures.
 * 3) Crystal of M3X-387, a crystalline race native to the Pegasus galaxy.
 * 4) Crystal skull, devices, built by the Omeyocan, with a function of transportation and Dimension shifting.
 * 5) Crystal Skull, the twenty first episode of the third season of Stargate SG-1.
 * 6) Unity, a crystalline race native to the Milky Way galaxy.