Cretaceous limestones from the basement o f the Neogene Mut Basin are strongly sculptured by borings, including mainly clionid sponge borings Entobia ispp., bivalve borings Gastrochaenolites torpedo and G. lapidicus, the polychaete boring Caulostrepsis taeniola and Meandropolydora isp. The borings are replaced subsequently; as a rule the succession begins with C. taeniola and terminates with Entobia isp. The discussed boring producers display various tolerance for light, energy and depth conditions, hence their succession may reflect environmental changes, related to marine transgression, proceeded upon rocky coast area. Since such a coast could be devoid of sedimentation for a long time, the possible reconstruction o f relative sea-level change may be inferred exclusively from nonsedimentological criteria i.e. from the succession of endolithic borings. Therefore the borings may be employed as useful tool in sequence stratigraphic procedure.