It's the rock swallowed by Cronos as a substitute for his son, Zeus, who grew up and overthrew him. It's also the rock in the corner of the Kabaah at Mecca, which is worshipped every year by millions of Muslims. It's the rock Sisyphus is constantly pushing up the hill, but never manages to get to the top. It's the rock in the Caucasus that the titan Prometheus is chained to, for daring to bring the gift of fire to humanity. It's the planet Saturn.