If you go to the harbor, you will usually find rocks lined up neatly along the beach. Often also found concrete structures in the form of tetrapods. Tetrapods are easy to find in coastal areas that have high waves.
The function of tetrapods is to break waves and protect land from abrasion caused by ocean waves. Installation of these tetrapods as a precaution if one day high waves crash causing unwanted things.
Like some unpredictable things in life. We can't prevent it, but at least we can control it.
This photo was taken using a Sony A6K mirrorless camera, when I was walking to the harbor with friends.