A carn was a small container, approximately five inches tall, used by the Ardanans to hold and preserve a type of bio-engineered, intellect-enhancing parasite. The carns were protected by a bio-magnetic field, allowing them to function as miniature stasis chambers.
Several of these carns were saved following the abandonment of Stratos in the late 23rd century, and kept in the museum at First City, Ardana. In 2377, Historian Vanov gave these carns to Captain Montgomery Scott, who had come to Ardana to help stabilize the failing anti-gravity engines on Stratos. He in turn gave them to the Starfleet Corps of Engineers team on the USS da Vinci, at which time one of the carns was opened and Crewman Fabian Stevens was infected.
According to Vanov and High Advisor Larin Nelois, they had no knowledge of the true nature of these carns. However, Ardana Council Spokesman Yaffie accused the two of intentionally trying to use the carns to create a new Sentinel.