Not all 12 of the Apostles remain standing. These sandstone columns formed over thousands of years. The sedimentary layer at ocean level is denser, harder, than many of the layers above it. Still, with timeless pounding of waves, the layer breaks down and, periodically, columns and arches that stood for millenia topple into the ocean. Had Cook arrived a few decades earlier, this formation may have taken on the somewhat less poetic name, 'The Baker's Dozen'.