Symbolism can be anything, a person, place or thing, used to portray something beyond itself.
It is used to represent or foreshadow the conclusion of the story. As one reads this novel, he or she will begin to recognize the way basic civilization is slowly stripped away from the boys. From the very beginning of the story the boys inwardly strip themselves of the remnants of the basic civilized world. Their hair becomes increasingly disheveled, long, and entangled with small twigs. Since the boys are left without any adult supervision they have to turn to their collective unconscious.