The ebb and flow of the tide is the breath of the sea, and the arrival of the waves brings dark shades to the beach. When the coast returns to calm and the tide finally disperses, it is as if nothing has happened and everything seems to have passed. However, the shells scattered on the beach reveal the secrets of the sea. They are the gift of the tide, and after the tide recedes, they are the only past that cannot be passed. Just as we cannot catch the gravel that slips through our fingers, we cannot stop the time that slips away - each moment is the next, and the world we see in our eyes is constantly being renovated. Yet, some things are not easily forgotten, they are memories of the past, yet they are precisely what will fuel the future.
Excerpts from "The Gift of the Tides
I really like this sentence describing beach shells too much, so I share it with you.