Core Crystals from War on Geminar
A Core Crystal is the heart and brain of the artificial human created by the Senshi civilization. The Core Crystal is inserted into an artificial body within a cocoon. The Crystal uses the cocoon to form a body of an artificial human. The Crystal will record all of the the artificial human experiences.
After the artificial body expires, it will have to be placed in a new body allowing it to retain the experiences and grow into a stronger version of the former self. The Core Crystal also creates its own personality making each core crystal unique.[1]
A Core Crystal can be placed inside a normal human body, however, the crystal will slowly end up consuming the person's body and personality merging the two until the artificial human's own body and personality becomes the dominant one of the two.[2]
The only three that are know to have core crystals in Geminar are Ulyte Mest, Mexiah Flan, and Babalun Mest. Out of the three, Mexiah and Ulyte are the only ones to show both personalities manifest into their physical forms of Doll and Rea Second.