Bone Titans are completely composed of the bones of fallen creatures. These bones are molded into the existing body of the Bone Titan, strengthening and enlarging the creature. The bones of the Bone Titan are often sharpened and even shaped by the Titan, for use as a weapon or tool.
Bone Titans, like all Titans, has a Titan's Core used for storing mana essential for its life. The Bone Titan's core, not unlike the Flesh Titan 's core, pulsates, sending mana throughout the body without the use of Titan Crystals.
Bone Titans, like Flesh Titans, are formed when exposed to a electrical or magical current. These may occur during thunderstorms or Magic Storms. If a large enough mass of people die in a relatively close position die, enough magical energy may be released to form a Bone Titan.Flesh Titans and Bone Titans form in almost the exact same manner. In some cases, a Flesh Titan and a Bone Titan may form from the same mass of corpses and may be interlinked. These creatures will often grow together, forming a hybrid.
Bone Titans, unable to extract mana from dead flesh, must hunt in order to survive. They will kill anything that moves, often killing Flesh Titans, Flesh Serpents, or even other Bone Titans native to the Blood Forest. Mana is absorbed into its core and bones are collected, further strengthening the beast.
A Bone Titan's purpose in life appears to be to grow as large as possible, searching far and wide for bones to add to its collection. Unlike a Flesh Titan, Bone Titans do not worry about rot and use much less mana to live, resulting in them having extended lives. A single Bone Titan may live up to twenty years if it finds enough energy to live.