Answer:
Piggy's death is stark, unemotional and totally lacking in any dignity. Piggy is compared with a dying pig, who doesn't even have the time to grunt and who's arms and legs continue to twitch even after death. His brains spill out on to a rock and then his body was unceremoniously flushed away by the sea. Compare this to the poetic description of Simon's body being escorted out to sea by a fringe of inquistitive bright creatures.