The article by the discoverers (2002) and publishers (2006) of the first Polish ducal bull is devoted to summing up the reflections on Polish metal seals. The main topics discussed are related to their chronology and functions. During the years 2002-2009 as many as five such seals were discovered. The authors are convinced all Polish ducal bulls should be dated to the times of Boleslaw III Wrymouth (after 1121). The presented typology of Polish ducal bulls was based on the varieties in the inscriptions and imagery, namely a standing figure of the ruler and two different depictions of St. Adalbert. Two types of seals were detected and their iconographic programmes were found to be connected with bracteates of Boleslaw Wrymouth. Attention is also paid to the find of a clay clump with several impressions of a gemma from the ducal palatium on Ostrów Tumski in Poznan. It is proved that the find was a clay seal, securing a chest or door. Clay seals were in use at Polish ducal court in the 11th/12th centuries alongside wax seals and bulls. This indicates not only a much more advanced development of seal signs than believed so far, but also existence of a certain system of them, and therefore also a hierarchy. The authors postulate that besides searching for the functions of bulls other than authentication of documents, it should also be considered whether their high number is not a remnant of an unsuccesful (because too early and discarded by successors) attempt at regulating internal relations and organisation of the state on the basis of document issued by the duke.