The long-term history of the geodynamo provides insight into how Earth's innermost and outermost parts formed. The magnetic field is generated in the liquid-iron core as a result of convection driven by heat carried across the core-mantle boundary and freezing of the solid inner core. Earth's magnetic field acts as a shield against energetic solar radiation, and therefore the geodynamo played an important role in the development and retention of our atmosphere, ultimately setting the stage for the evolution of life. A new analytical approach, using single silicate crystals that host minute magnetic particles, can reveal heretofore hidden aspects of Earth's magnetic history. This method is being used to address some of the outstanding questions regarding the long-term behavior of the geodynamo.