In modern marine environments, coral reefs are the most biodiverse ecosystems, but they are threatened by increasing ocean anoxia and acidification associated with intense climate warming. During the Phanerozoic Eon, metazoan reef ecosystems varied significantly in response to dramatic environmental changes, especially during mass extinction events. Studies of these deep-time examples and comparisons with modern coral reefs under similar environmental conditions can provide insights into optimal management approaches for modern reefs. We therefore propose a session on this topic that will attract international participants from fields such as sedimentary geology, palaeoecology, palaeoclimatology, geobiology and conservation biology.