Rongorongo, said to have originally been called "kohau motu mo rongorongo" ("lines of inscriptions for chanting out"), is the only pre-contact indigenous Austronesian system of glyphs that appear to be true writing or at least proto-writing. They consist of around 120 glyphs, ranging from representations of plants to animals, celestial objects, and geometric shapes. They were inscribed into wooden tablets about long using shark teeth and obsidian flakes. The wood allegedly came from toromiro and makoi trees, which is notable given that Rapa Nui was completely deforested at the time of European contact. 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.