Survival requires sacrifice. But what if the price is an entire world?Their home is cold and dying, choked by the toxins of their own progress. Now, an advanced alien species looks toward the Third Planet-Earth-with hope and fear. They see a fertile paradise, but one that is hostile, hot, and dominated by massive, predatory reptiles.The choice is stark: die in the heat, or remake this new world in their own image.As they descend to alter the climate and purge the planet of its prehistoric masters, they set in motion a chain of events that will echo through geological time. A Symbol of Time weaves palaeontology and astronomy into a chilling tale of survival. As the new masters of Earth terraform the planet, the question remains: does high intelligence inevitably carry the seeds of its own destruction?