An energy pyramid is a diagram that shows how energy is passed on in an ecosystem and how much energy is passed between different organisms in an ecosystem. Only 10% of energy is passed between different levels of the pyramid with the other 90% being used by the organism in the previous level for needed bod y functions. This also explains why a pyramid is the shape used for this diagram, because it shows the shrinking in the amount of energy available to organisms as more organisms are added into the ecosystem.