What do the boys do when Piggy mentions signal fire? What is piggy's fear?

The boys run up to the top of the mountain and unleash a fiery inferno. Piggy fears being killed on the island. He well knows that in a Darwinian society like this, he is the least fit and considered the most expendable. When Piggy sees the chaos of the fire the boys unleash at the top of the mountain, Golding writes, "Piggy stared into Hell." Indeed, this island is Hell for a boy like Piggy.