Soils are home for a wide variety of organisms such as worms and other tiny animals such as insects, arthropods (like spiders and millipedes). there are also organisms such as fungi and bacteria. collectively these organisms serve two very important services to/in the soil. what are these services?

One service is aeration (by churning the soil. It's important to recognize that roots of plants require aerated soils or them to function due to biological processes such as active transport of nutrient that require oxygen). The second service is nutrient cycling (they decompose dead matter into nutrients that are absorbed by plants).