A problematic cap-shaped metazoan from the Lower Cambrian of Estonia

The cap-shaped Scenella(?) discinoides Schmidt, 1888 is redescribed on the basis of the type material from the Lower Cambrian of Estonia and assigned to a new genus Estoniadiscus. Shell morphology, the apparent phosphatic composition and the presence of probably setigerous tubes perforating the shell indicate that Estoniadiscus is neither a mollusc related to Scenella Billings, 1872, nor a chondrophorine hydrozoan. Following comparison with several other problematic Cambrian metazoans it is concluded that Estoniadiscus may be a stem group brachiopod.