Grain growth simulations using the microstructure simulation system Elle have been performed in materials with a pre-existing grain shape preferred orientation. As might be expected, the microstructure is completely modified by the end of the experiment, and grain areas have increased by a factor of seven. The area of material swept by the migrating grain boundaries was monitored, and it was found that at every stage, virtually all of the grains which survived the grain growth process contain one and only one core of unswept material. Remarkably these remnant unswept cores preserve a useable record of the grain size and orientation of the original grains. This work suggests that it may be possible to see past a grain growth episode to estimate the original grain shape and grain size of the polycrystal, and perhaps even reconstruct the grain boundary kinematics. The identification of unswept cores also has the potential to help unravel the evolution of grain boundary chemistry during grain boundary migration.