The organisms directly responsible for recycling and returning most minerals within an ecosystem are called decomposers.

Here's why:

* Decomposers are organisms like bacteria and fungi that break down dead organic matter (plants, animals, waste).

* This breakdown process releases nutrients like nitrogen, phosphorus, and carbon back into the soil and atmosphere, making them available for other organisms to use.

* Without decomposers, nutrients would become trapped in dead matter, limiting their availability for new life and disrupting the entire ecosystem.

While other organisms like plants and animals play roles in nutrient cycling, decomposers are the crucial link that ensures the constant flow of essential minerals through the ecosystem.