Piggy's glasses helped create a fire which brought some hope to the island and that rescue will be on it's way. The glasses represents the power in society.
The boys make an effort to figure out what the beast could and where is it would be located. some suggest it may be inside of all of them.
The shell could be used to call others for a meetings suggested by Ralph. This represents the political power and order on society.
Jack kills some pigs for some meat. The pig huntings sumbolizes the blood lust that over takes Jack and theother boys.
The growth of Ralph's wild hair symbolizes the breakdown of law/order and discipline. This demonstrates how the boys are far away from human social development.
The dead parachutist was a symbol of war and people fight against each other. The man landed on the island after his plain was shot down and there explosions going in the sky. The man also emphasized the fall of mankind.