The chronology of the Persepolis finds was traceable largely through the inscriptions on seals, wall pegs, and foundation slabs, that were discovered. Each usually bore the name of the Achaemenid ruler of its time. Cylinder seals, generally made of stone, often depict, among other subjects, martial or hunting scenes, rituals and offerings, or fights between animals. The royal seals of Darius and Xerxes always depict a king victorious in his fight with ferocious animals or monsters, a scene also depicted in the royal reliefs.