Tortoikoi

A beautiful fish with long, flowing fins that is surrounded by a shell. The Tortoikoi is symbolic to many cultures as it represents a unified balance due to its mating habits. Each Tortoikoi is born either black, with a with shell, or white with a black shell. The interesting thing is that when seeking out its mate, a Tortoikoi will only ever choose a mat with designs that oppose its own, sometimes, even the designs on the shell are similar. The shell designs are unique to each Tortoikoi and used by sapient races to identify each Tortoikoi similar to the way they'd use a fingerprint to identify one another.