The skull's shape takes its cues from the brain's topography

I recently received the brain specimen pictured above from an outside institution in a form I had never seen before: with the skull cap still attached! If you look closely, you can see how the subtle undulations of the skull's inner surface coincide with the gyral pattern of the brain's outer surface. As the skull ossifies during development, it seems to adjust to the pattern present on the brain surface. That patterning persists for the rest of one's life. Cool.