The thin layer of Earth in which living organisms are found is called the biosphere.

It encompasses all life on Earth and includes:

* The atmosphere: The layer of gases surrounding the Earth.

* The hydrosphere: All the water on Earth, including oceans, lakes, rivers, and groundwater.

* The lithosphere: The Earth's solid, rocky outer layer, including the crust and upper mantle.

While the biosphere is relatively thin compared to the Earth's overall size, it is incredibly diverse and plays a vital role in regulating the planet's climate and environment.