 Although of the surviving two dozen tablets, a few were made from trees introduced after European contact, as well as wood originating from European ships and driftwood.Rapa Nui also has a very rich assemblage of petroglyphs largely associated with the "tangata manu" ("birdman") cult of Makemake.Although some rongorongo glyphs may have been derived from these petroglyphs, rongorongo does not appear in any of the abundant rock carvings in Rapa Nui and seems to be restricted to the wooden tablets.