This rock is recognizable by its white color; the great builders have chosen it for their most edifying monuments. But even more surprising, it is born from the living and has maintained a filial relationship to it… This rock, which covers more than half of the Earth’s surface, is limestone! To unlock its secret, we will study the living organisms that make it up off the cliffs of Etretat, we will probe the ecosystem of the Dover region in England to get a grasp of its influence on the plant world. On Vancouver Island in Canada, we will explore galleries and caves where the mineral hosts a flourishing life. We will lose ourselves in the Catacombs of Paris. We will discover its harsh extraction in the quarries of Al-Minya in Egypt. In Namibia, we will walk in the footsteps of our distant limestone-dependent ancestors. Finally, off the coast of Florida we will be interested in a very strange animal made of flesh and rock.