A caterpillar can eat up to three hundred times its own weight in a day, devastating many plants in the process, continuing to eat until it’s so bloated that it hangs itself up and goes to sleep, its skin hardening into a chrysalis. Then, within the chrysalis, within the body of the dormant caterpillar, a new and very different kind of creature, the butterfly, starts to form. This confused biologists for a long time. How could a different genome plan exist within the caterpillar to form a different creature? They knew that metamorphosis occurs in a number of insect species, but it was not known until quite recently that nature did a lot of mixing and matching of very different genome/protein configurations in early evolutionary times. Cells with the butterfly genome were held as disclike aggregates of stem cells that biologists call 'imaginal cells', hidden away inside the caterpillar’ all its life, remaining undeveloped until the crisis of overeating, fatigue and breakdown allows them