And aren't we glad they do. This group of useful critters are mostly bacteria and fungus , but also, according to our sources, includes maggots, dung beetles, and earth worms. Without them there would be a lot of dead bodies lying around. They're like carnivores and herbivores, because they also have to get their energy from the cells of animals or plants. The difference is they prefer their food dead - very dead.
Some animals can eat plants and other animals.
So you could say they are both a herbivore and a carnivore. That's the way humans are. We can eat plants and we can eat meat. Well, la tee da. It must have been too difficult for biologists to say herbicarnivore or carniherbivore, so they decided to call humans, and others like us, omnivores .