A decomposer is an organism that breaks down dead plants and animals, returning essential nutrients to the soil. This process is vital for ecosystems, as it helps recycle matter and supports new plant growth. Common decomposers include bacteria, fungi, and certain insects, which work together to break down organic material. Decomposers play a crucial role in the food chain, as they help maintain the balance of ecosystems. Without them, dead matter would accumulate, and nutrients would remain locked away, making it difficult for new life to thrive. Their activity ensures that energy flows through the ecosystem, benefiting all living organisms, including plants and herbivores.