 A large spherical vestibule does not exist in aquatic or generalist (both land and water) snakes, only in snake species that burrow.A spherical vestibule contains a large saccular otolith, which transmits vibrations to the snake's brain.Due to a spherical vestibule, the "Dinilysia patagonica" was a species especially sensitive to low-frequency ground vibrations rather than airborne frequencies.