Traditionally, Vulcans would craft such items from volcanic glass, jasif crystal or polished tir-nuk wood. The Vre'katra was a reminder of the death of the departed, and usually placed within a family shrine near the Vulcan's estate, where the ancestors are both honored and remembered. Such shrines could contain hundreds of Vre'katra that covered generations of ancestors. However, only a few of these were actually built to contain the katra, or life essence of a Vulcan, and in modern times, the ability to do so was thought by most to be myth and rumor. (Last Unicorn RPG module: The Way of Kolinahr: The Vulcans)
A group of Vulcan dissidents known as the Sakethans, who left Vulcan hundreds of centuries ago, used katric arks, which were placed inside their burial mounds. (TNG - Mirror Universe novel: The Worst of Both Worlds)
- The vre'katra seem to be related to the receptacles used by Sargon and his people.
- The TOS - Vulcan's Soul novel: Exodus refers to one such receptacle as an Urn of Memory.