Standing at the top of the Pen Hir cliffs, one can see the Tas de Pois, a string of five granite pyramids, actually the summits of an underwater mountain range, caught in the currents and waves of the Atlantic. In spring and summer, small horizontal platforms on the cliffs may be covered with grass and the occacional tuft of purple heather, but most of the time the cliffs are invaded by seagulls and cormorans building their nests, breeding, and lavishing their guano on the rocky sites.