From Destinypedia, the Destiny wiki
Cryptoliths are Hive structures created and utilized by Xivu Arath, the Hive God of War, in order to corrupt the enemies of the Last City and turn them into mindless and enraged champions for her army known as the Wrathborn. They are present on the Moon, Tangled Shore, and deep within the Dreaming City.
Like most Hive architecture, Cryptoliths are partially biological, growing like plants wherever they are seeded. When dormant, they lie still and are mostly hidden below ground; when activated, they rise up and begin glowing, and various pieces of their outer shell begins to move. They are considered hard to remove, such as with a Cryptolith at the Reef that attempting to do so would destroy the Tangled Shore. Cryptoliths each also possess the ability to open up and reveal a portal to the Ascendant Realm, presumably even Xivu Arath's throne world.
Fall of Torobatl
At an unknown point in time, the Cryptoliths were utilized by Xivu Arath in her invasion of the Cabal capital world of Torobatl after Umun'arath summoned her through a Hive ritual. As the Cabal attempted to repel the incoming Hive army, the city was overtaken as the Cryptoliths emerged began infecting the area.
Rise of the Wrathborn
List of appearances