Here's why:

* Lack of Life: Rocks don't possess the characteristics of living things like growth, reproduction, or metabolism.

* No Internal Processes: Rocks don't have internal processes like those found in living organisms.

* Lack of Movement (on their own): While rocks can be moved by external forces like wind, water, or gravity, they don't move independently.

However, it's important to note that the concept of "inanimate" can be a bit nuanced. Some might argue that rocks are part of a dynamic geological system and therefore not entirely "inert."

Ultimately, whether you consider a rock inanimate is a matter of perspective.