Now that we’ve covered the most important organisms in the soil food web from bacteria to birds, we’ll circle back to some peripheral players. First up is algae. Algae are single-celled or thread-like photosynthetic organisms. Most of us associate algae with water – lakes, rivers, even aquariums. But there are terrestrial algae that live in soil, as well.

A unique feature of algae is that it can produce its own food using the sun’s energy, which means they’re not as dependent on organic matter in the soil for food. This also explains why they are mostly found near the surface of the soil, within reach of the sun. Their direct impact on the soil ecosystem is relatively small; their only predators are certain nematodes. However, they release slimes and mucus that help bind soil particles together, creating soil structure. And of course, when they die off, they contribute to the organic matter in the soil.

Another contribution of algae is producing new soil. The organisms attach to rock and produce carbonic acids that weather the rock, releasing minerals into nearby soil. Lichens, composite organisms formed from the symbiotic relationship between algae and fungus, also weather rock into soil. In lichens, the fungi provide the necessary moisture for algae to survive, while the algae provide food to the fungi. This lichen relationship is really something to like!