Present-day marine habitats are often the result of long-term natural trajectories of change and impacts by anthropogenic pressures. Impacts are measured with reference to the good environmental status of a baseline that, however, is presently shifting away from the pristine state. The course provides the conceptual framework and the fundamentals for the use of dead shell assemblages and recent fossil association in the reconstruction of the ecological history of marine habitats. Lectures will cover the main aspects of sampling and interpretation of benthic dead assemblages, including the basis of substrate-benthos relationship, taphonomic analyses of mollusks, radiocarbon dating, and benthic bionomics. Some case studies conducted in the Mediterranean and in the Indian Ocean will be presented.