The first animals on Earth emerged about 600 million years ago, and 60 million years later, those simple early animals evolved into wildly different directions, branching out into a diverse menagerie of complicated new forms and conquering new ecological niches. And it may have taken off because some of those early animals evolved a bizarre new ability: pooping. According to a recent study, the first poo pellets helped spread nutrients to deeper parts of the ocean, fueling the evolution of bigger animals in more diverse ecosystems. Without that biological pump, the deeper reaches of the ocean would be much less habitable than they are now. Kimming and Bicknell argue that when animals evolved the first digestive systems, they sent the first poop drifting down through the depths, which gave the early biological pump a sort of kickstart.