If you hand an adult a lump of clay, they're likely to respond by fashioning something representative out of the raw material. For the most part, they'll simply forge an object that signifies something "real" in the world, even if that something is as abstract as an emotion or an energy. A child, on the other hand, will just as often produce something totally without semiotic meaning, a shape or a mass that represents nothing that exists outside of their imagination. Or else, they'll eat it or throw it or ignore it, wholesale.