Clay is a particularly surprising rock. Soft and fragile when dry, it is malleable when in contact with water and can freeze permanently under the action of fire. Thanks to its peculiar properties, clay influences living things like no other rock. It has changed the course of history since Men have first discovered it. To better understand its particularities, we will go to India to meet researchers, potters and brick makers. In France, we will delve into the heart of the material to unlock its secret. In the United States, we will follow the work of scientists that highlight the role of clay for our planet’s ecosystems’ survival. In Namibia, we will accompany dust hunters and termite specialists.