Petroglyphs are pictures carved into rock, and Easter Island has one of the richest collections in all Polynesia. Around 1,000 sites with more than 4,000 petroglyphs are catalogued. Designs and images were carved out of rock for a variety of reasons: to create totems, to mark territory, or to memorialize a person or event. There are distinct variations around the island in the frequency of themes among petroglyphs, with a concentration of Birdmen at Orongo. Other subjects include sea turtles, Komari (vulvas) and Makemake, the chief god of the "Tangata manu" or Birdman cult.