Piggy lighting the fire symbolizes his commitment to order, civilization, and reason in the face of chaos and savagery on the island. It also represents his attempt to maintain hope for rescue and a return to civilization.
The significance is that the shell used to represent organisation, the glasses (piggy's specs) represent hope, without them, there would be no fire.
When Jack accused Piggy of not helping much with the building of the fire in chapter2: Fire on the Mountain Simon defended Piggy by mentioning that they had used Piggy's spectacles to light the fire so he had helped in that way.
his glasses
The other two characters who helped keep the fire burning in "Lord of the Flies" were Piggy and Simon. Piggy was responsible for suggesting the idea of using Piggy's glasses to light the fire, while Simon helped to gather wood for the fire.
Ralph wants to get Piggy's specs back and Piggy wanted to kill Jack there and then.
They took Piggy's glasses, and fire from Ralph's camp.
Piggy suggests building the fire on the beach by using the lenses of the boys' glasses to focus the sunlight and start the fire. He recommends using the lenses like a magnifying glass to create the fire. Eventually, they successfully build the fire on the beach.
It is Jack's idea to use Piggy's glasses to start the fire. Jack steals the glasses right off of Piggy's face without even asking him first.
they use his "specs" to focus the sunlight to set the wood on fire.
Piggy's glasses have the same significance in the 1963 movie as they do in the later 1990s remake and in the original novel. Piggy's glasses serve to identify him as an outsider. He is the only boy on the island who wears glasses. The wearing of glasses is also often used as a literary (and cinematic) device to indicate intelligence. Piggy's glasses also provide the means to make fire and they provide an excuse for conflict between jack's tribe and Ralphs group. The breaking of one lense of Piggy's glasses when Jack pushes him over has great symbolism as does the complete shattering of them when Pigy is killed by the boulder.
The boys use his specs(glasses) to direct the sunlight to the sticks on the mountain and make a fire.
Piggy and the twins come to Ralph with a feast of properly ripened fruit.