Organisms that break down dead or decaying matter are called "decomposers." They play a vital role in ecosystems by recycling nutrients and ensuring that organic matter is returned to the soil. Decomposers include various bacteria, fungi, and some insects like earthworms. By breaking down dead plants and animals, these organisms facilitate nutrient cycling, helping maintain soil fertility and promoting plant growth. Without decomposers, ecosystems would be overwhelmed with organic waste, leading to reduced biodiversity. Their function is essential for sustaining life, making them a fundamental component of ecological health and balance.