Apophenia

A young child and the final remaining sea creature in Alterna, called the "Alternan Angel" by Callie due to the miraculous circumstances that allow them to survive the polluted waters. They have spent their entire life exploring the ruins humans left behind deep within the depths of Alterna with their only friend and caretaker, ORCA.

Once passed the age of maturity or if the body sustains enough damage, they begin an instinctive journey to the bottom of Alterna's polluted ocean and root themselves to the earth. Starting the beginning stages of rebirth and reforming themselves into a young infant, losing their memories in the process. A juvenile sea creature will emerge from the polyp and spend its time in the water, absorbing nutrients and begin their ascent back to the surface where ORCA waits. 

They continue this cycle of life and death, absorbing more and more of the crystal remains of the human will during each cycle, causing them to develop subhuman traits as time marches on.