A prominent bed, containing brachiopods and ectoproct bryozoans, is widely distributed within the Maltese Islands, being associated with a coralline algal rhodolite bioherm. This bed provides a useful stratigraphic marker horizon at the base of the Upper Coralline Limestone Formation. Samples taken from the bed at localities in Malta and Gozo have been examined and their contained biodata studied. Distribution analysis of the bryozoan growth-forms present has permitted recognition of four assemblages, dominated by cellariform, vinculariiform, encrusters, and cellariform and vinculariiform bryozoan growth-forms, respectively. Morphological variations and distributions of brachiopods contained within the samples were also examined and these were compared with the bryozoan growth-form distributions previously obtained. An interpretation of the palaeoecology of the four common brachiopod species, Terebratula terebratula, Aphelesia bipartita, Argyrotheca cf. cordata and Megathiris decollata, is offered partly on the basis of present-day brachiopod ecology but mainly on the basis of information gained for the bryozoans. Interpretations of the palaeoecology of several other common invertebrate genera, also based on the bryozoan growth-form distributions, are also presented.