Regarding the shape of the magatama, there is a theory that the magatam was originally made in the form of an animals tusk, a theory that maintains it represents a yin-yang diagram (a figure of Taiji), and a theory that it represents the fetus at an early stage of development in the mothers womb.
その形状は、元が動物の牙であったとする説や、太極図を表すとする説、母親の胎内にいる初期の胎児の形を表すとする説などがある。