Cruciforms resemble in shape and proportion the crucifixes that are central to the human religion of Christianity. Their texture is similar to that of soft coral, and they give off a bioluminescent pinkish glow. Their back surfaces are entirely flat and smooth, lacking any obvious adhesive properties, and a set of knobs on the top "arm" of the cruciform allow them to be easily tied to necklaces and lanyards.
The cruciforms lived on the walls of Hyperion's labyrinths. After being placed on the skin of a host, the parasite grows root-like fibers throughout the body, and copies the DNA and memory samples from the host; after growing into a host, the cruciform shares its host's DNA. After the accidental or natural death of the host, the parasite is able to recreate the host's body and mind, repairing bodily damage and thus resurrecting the individual. The cruciform's regenerative powers are truly astounding: so long as a even tiny fragment of host tissue and cruciform matter remains, the host will be re-created. The procedure is not flawless; with each consecutive resurrection more memory and mental capabilities are lost, and the body starts to change to a neutered, stunted form.
Once a cruciform bonds to a host, it is impossible to remove through surgical or other conventional means. There are only three known ways to remove a cruciform from a host body:
- By subjecting the body to sustained immolation over the course of numerous resurrections, so that the body is weakened enough for the cruciform to be removed,
- By having the Shrike remove a cruciform manually from a body,
- By having the host become infected by the Aenea virus.
The cruciforms were created by the TechnoCore in order to keep a population of humans alive in order for their brains to serve as biological computers for the TechnoCore. For this reason they were bred in the planetwide labyrinth of at least one labyrinthian world, namely Hyperion.
The Bikura, an indigenous tribe of humanoids native to Hyperion, originated as a group of settlers who encountered the cruciforms, degrading over time due to repeated resurrections into physically and mentally stunted versions of their former selves.