I’ve been an earthworm fan for decades. At my Oakland, California home I dump vegetable scraps into a big plastic bin with worms. Once or twice a year I collect incredibly rich worm compost, teaming with roly-poly bugs (isopods), worms — and billions of critters I can’t see. My garden plants love it, and it’s free.
In agricultural soils, worms (different kinds, but worms nevertheless) can contribute significantly to soil respiration with a direct and sharp increase in the amount of carbon dioxide (CO2) released, as the number and length of worm canals increases. It turns out this soil respiration is critical to plant health.