In the 1930s, Dr. Javier Cabrera, a medical doctor, received a gift of a strange stone from a local farmer. Dr. Cabrera was so intrigued that he collected more than 1,100 of these andesite stones, which are estimated to be between 500 and 1,500 years old and have become known collectively as the Ica Stones. The stones bear etchings, many of which are sexually graphic (which was common to the culture); some picture idols and others depict such practices as open-heart surgery and brain transplants. The most astonishing etchings, however, clearly represent dinosaurs - brontosaurs, triceratops (see photo), stegosaurus and pterosaurs. While skeptics consider the Ica Stones a hoax, their authenticity has neither been proved or disproved.