A dentist who examined the upper right maxilla found with the skull determined that the skull was that of a child aged 4.5 to 5 years. The volume, however, of the interior of the Starchild skull is 1,600 cubic centimeters, which is 200 cm³ larger than the average adult's brain, and 400 cm³ larger than an adult of the same approximate size. The orbits are oval and shallow, with the optic nerve canal situated closer to the bottom of the orbit than to the back. There are no frontal sinuses. The back of the skull is flattened. The skull consists of calcium hydroxyapatite, the normal material of mammalian bone.