Cryptum

Cryptums, or Warrior Keeps, were Forerunner objects created by the Prometheans. A Cryptum is a sealed capsule where a high-ranking Warrior-Servant would enter self-imposed exile as punishment for failure or dishonor, involving a state of meditative hibernation known as "timeless xankara". During this time, the Forerunner would become unaware of the physical world around him, and could remain in a state of suspended animation for thousands of years. Cryptums required an extraordinary amount of force to breach once sealed. They denied access to every species except Forerunners.

Background
While the Cryptum preserved the consciousness of the Forerunner inside for an indefinite period, the Forerunner's physical body would still deteriorate, albeit at a significantly reduced rate, in a process similar to natural mummification. The body would shrivel and lose most of its fluids. Once the Forerunner was removed from the Cryptum, the body would be placed in a restorative bath, and the body's supply of electrolytes, nutrients and other essentials was thereby replenished. The body's muscle structure would then be regenerated, a process requiring several days.

Although typically inert, when activated, a Cryptum is capable of powered flight and is capable of scanning its surrounding environment.

The nature of a Cryptum was unknown to most Forerunners, including Bornstellar Makes Eternal Lasting. However, he was aware that the violation of a Cryptum invoked dire consequences, one of which was angering the powerful Prometheans.

A Cryptum was discovered in Djamonkin Crater by the young Forerunner Bornstellar Makes Eternal Lasting, containing the meditating Didact. Another Cryptum, containing an unidentified entity, was discovered over 100,000 years later by John-117 and the AI Cortana on the Forerunner Shield World Requiem.

Trivia
The millennial seal on the Didact's Cryptum was sealed by two forces known as "The Wisdom of Harbou" and "Strength of Lang". Who or what Harbou and Lang were is unknown. However, they appear to be a reference to the German actress and author Thea von Harbou and the film producer and screenwriter Fritz Lang, who were married and made several films together.

List of appearances

 * The Forerunner Saga
 * Halo: Cryptum
 * Halo: Primordium
 * Halo 4