In Polynesia, rock art is dominated by petroglyphs, rather than paintings, and they show less variation than the rock art of Near Oceania and ISEA. In the western Polynesian islands nearest to Island Melanesia, rock art is rare (like in Tonga and Samoa) or are absent entirely (like in the Cook Islands). However, petroglyphs are abundant in the islands in the further reaches of the Polynesian triangle, particularly in Hawaii, the Marquesas, and Rapa Nui. Rapa Nui has the densest concentration of engravings in Polynesia as a whole; while the Pu'uloa petroglyphs site in Hawaiʻi has the largest number of petroglyphs in a single site at over 21,000 engravings. Polynesia also features megalithic sacred ceremonial centres generally known as "marae".