Marine paleoecology reconstructs past ecosystems and communities to establish historical baselines, distinguishing natural variability from human-induced changes. By analyzing coral and sediment cores, isotopic compositions, fossil remains, and ancient DNA, we infer past biodiversity, climate conditions, and ecosystem dynamics. Techniques such as geochemical analysis of coral skeletons, environmental DNA (eDNA), and species distribution modelling provide insights into historical reef health, environmental shifts, and species responses to climate change and anthropogenic disturbances. Paleoecological data help identify shifting baselines, assess ecosystem resilience, and guide conservation by defining realistic restoration targets.