 The discovery of a colossal head at <unk> <unk> in the nineteenth century spurred the first archaeological investigations of <unk> culture by Matthew <unk> in 1938 . Seventeen confirmed examples are known from four sites within the <unk> <unk> on the Gulf Coast of Mexico . Most colossal heads were sculpted from spherical boulders but two from San Lorenzo <unk> were re @-@ carved from massive stone <unk> . An additional monument , at <unk> <unk> in Guatemala , is a throne that may have been carved from a colossal head . This is the only known example from outside the <unk> <unk> . 
