The soil, a thin layer covering the Earth's crust, is crucial for life on our planet. One teaspoon of soil contains more living organisms than there are humans on Earth, and 25% of the world's biodiversity is found in the soil. Healthy soil can capture carbon, reducing the amount of CO2 in the air, a greenhouse gas that contributes to global warming. This process helps regulate the climate and supports the growth of plants, which in turn provide food and oxygen for all living beings. Soil functions as a complex ecosystem where various organisms work together. Detritivores, such as earthworms and insects, break down organic matter into smaller elements. These elements are then consumed by decomposers like bacteria, which transform them into minerals, water, and CO2. These nutrients are absorbed by plants, helping them grow and thrive. When it rains, water seeps into the soil, acting as a water reserve for plants, fungi, and other organisms. Additionally, soil helps filter water, especially through the roots of trees, which can purify and store water naturally. Minerals in the soil are essential for the growth of all living organisms. They provide the necessary nutrients for plants, which in turn support the food chain. Freshwater, the only type of water humans can use to live, is a precious resource that must be carefully managed and protected. The importance of soil and water is highlighted in the Revue Salamandre Junior article "Ma planète - La vie sous terre, ça ressemble à quoi?" This educational material is part of a series of videos created by the Revue Salamandre Junior to help children aged 8-12 better understand the challenges facing our planet. The Revue Salamandre is an independent, non-profit publisher dedicated to promoting a love for nature. Through its publications and videos, it aims to educate people about the natural world, from small insects to large animals, and from incredible plants to the ecosystems that support them. By making nature accessible and engaging, the Revue Salamandre encourages a deeper appreciation of the environment and the importance of preserving it for future generations.