Do you know why pebbles on the beach are round? Owing to the constant battering by the sea waters, pebbles become smooth and round. Originally, they are part of much larger rocks, but various natural phenomena such as earthquakes and volcanoes have gradually broken them down. Caught in the movement of the sea and rubbed against other hard materials, the pebbles lose their irregular edges and acquire a roundish shape. Many of the rocks you see today are actually going to turn into cute pebbles in the coming centuries.