Why th top of an energy pyramaid does not have a arrow showing energy going back down to the bottom?

An energy pyramid shows the flow of energy through trophic levels in an ecosystem. The top of the pyramid represents the highest trophic level, where energy is transferred from organisms at lower trophic levels to those at higher trophic levels. The absence of an arrow going back down to the bottom is because energy is not transferred back down the trophic levels; instead, it is lost as heat through processes like respiration and metabolism.