efficient at what? what's the measure, utility function, what are nature's KPIs? :) utilizing energy gradients? maybe, but there's plenty of that on Mars yet i

efficient at what? what's the measure, utility function, what are nature's KPIs? :) utilizing energy gradients? maybe, but there's plenty of that on Mars yet it's barren. so probably certain ecosystems can be more or less efficient at this, right?