Ever decreasing stones

Stones on the seashore between Spiddal and Inverin, worn smooth and round by the sea, and getting smaller year after year. Picture taken last Sunday morning with a Canon 5D DSLR, Canon 17-40mm zoom lens @ 40mm, 0.9 Neutral Density filter (reduces light by 3 stops), ISO50, shutter speed = 4 seconds. Manfrotto tripod fitted…