We all know the adage 'One person's trash is another person's treasure,' so how about 'one creature's poop is another creature's food?' It sounds icky and unpleasant, but to the creature who needs it to survive, it's wonderful.
Flies rush to the odor of fresh poop - it ensures their survival. They lay their eggs in it, so their larvae have something to feed on when they hatch. Perhaps flies might wonder how our babies can eat pureed apples!
Molds grow on animal feces too, using it as a substrate from which to gain sustenance, and at the same time breaking it down. One of them is known as called hairy poop mold - I'm sure we can all picture it. Microbes such as this are a good thing - they're the perfect way to 'get rid of' the by-products of each species and keep the nutrients in the system without them causing disease or spreading illnesses.
Waste is part of the process of life and recycling, so waste is not the end-product, but a stage in a process that keeps re-packaging nutrients into something useful. Decomposition and the breaking down of nutrients is a normal, natural process to sustain life on earth.
The idea of something being called waste relates to its usefulness (or lack thereof) to its producer. Many organisms benefit and depend on the by-products of others, which to them is not waste, but life-giving. So let's 're-package' the idea of waste!
Waste to me is anything that is unnecessary, not sustainable and not recyclable i.e. some of the things WE humans create. This is waste.