In western Micronesia (Palau, Yap, Guam, and the Northern Mariana Islands), rock art primarily consist of paintings on high cave ceilings and sea-facing cliffs. They are very similar to APT in terms of their motifs as well as their relatively inaccessible locations. Common motifs include hand stencils, faces, turtles and fish, concentric circles, and characteristic four-pointed stars. Petroglyphs are rare, but mainly consist of human forms with triangular bodies without heads or arms. This is believed to be connected to the funerary rite of removing the heads from the bodies of deceased relatives. A notable megalithic tradition in western Micronesia are the "haligi" stone pillars of the Chamorro people. These are capped stone pillars which are believed to have served as supports for raised buildings. They are associated with the Latte period (900 to 1700 CE), when a new wave of migrants from Southeast Asia reintroduced rice cultivation into the islands. Another megalithic tradition is also that of the rai stones, massive doughnut-shaped discs of rock which were used as currency in Yap.