How do pill bugs return nutrients to the ecosystem?

They recycle nutrients back into the ecosystem by eating and digesting. Pill bugs play a role in decomposition. After feeding on decomposing plants, they return the organic material to the soil so it can be further digested into nutrients for growing plants. They're also able to remove toxic metals from the soil during the digestion process.

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.