Consider the battle between the caterpillar and the butterfly within it. A caterpillar carries within it, throughout its caterpillar time, something scientists call imaginal discs. These discs are grown while the caterpillar is forming inside its egg, before it hatches. There are discs for each of the various body parts the butterfly will need- eyes, wings, legs etc. In some species, the discs remain dormant until the caterpillar’s transformation to butterfly begins, and in others they activate sooner. At some point in nature’s timing, when the caterpillar has fed itself on sometimes hundreds of times its weight in leaves per day, it hangs itself up, its skin begins to harden into a chrysalis or it spins a protective cocoon, and it starts to dissolve its own inner tissues. The imaginal discs activate and begin to feed on the soupy biomass inside the chrysalis. What is left of the...