Platinum is a dense, malleable (can be thinned), ductile (can be stretched), shiny gray-white transition metal that is rare enough to be deemed a precious metal.
"Ahu" are stone platforms on which many moai sit. There are 313 known ahu and 125 of these carry moai. The biggest, Ahu Tongariki is 220 m (720 ft), and had the most (15) and tallest moai.