Stromatolites are the most intriguing geobiological structures of the entire history of the earth since the early beginning of the fossil record in the Archaean. Traditionally, stromatolites and related microbial sediments are interpreted as biosedimentological remains of biofilms and microbial mats. Stromatolites are important environmental and evolutionary archives that give us plenty of information on ancient habitats, biodiversity, and evolution of complex benthic biosystems. However, many aspects of the formation, biology, and geobiology of these structures are still cryptic and poorly understood. The symposium is dedicated to Ernst Louis Kalkowsky (1851–1938), who introduced the terms “Stromatolith” and “Ooid” to the earth science community in 1908.