A Galaran data crystal is a small device created by the Galaran. Data can be stored on the crystals, specifically memories, and can be transferred, removed and imprinted between human beings. Initially designed as a quick and efficient way to gain and share knowledge between the Galaran people, it was developed by Galaran scientists, but was taken over by the military late in the production process.
In 2006, SG-1 visited Galar and Lt. Colonel Cameron Mitchell became friends with Dr. Reya Varrick, one of the developers of the crystal. He woke up one morning to find her blood on his hands and memories of her murder. During the investigation into his guilt, Varta gave Teal'c and Dr. Daniel Jackson a data crystal that would help them prove Mitchell innocent. (SG1: "Collateral Damage")