Here's why:

* They break down dead organisms: Bacteria play a crucial role in decomposing dead plants and animals, as well as waste products. They break down complex organic matter into simpler substances, releasing nutrients back into the environment.

* They are essential for nutrient cycling: The nutrients released by bacteria are then available for other organisms to use, completing the cycle of matter in the ecosystem.

* They support other food web levels: Decomposers like bacteria are the foundation for the entire food web, as they create the necessary nutrients that support producers (plants) and consumers (animals).

While some bacteria can be harmful, many play a vital role in maintaining healthy ecosystems and supporting life on Earth.