How does the Golding’s use of imagery here reflect Simon’s symbolic role in the novel?

The water rose farther and dressed Simon’s coarse hair with brightness. The line of his cheek silvered and the turn of his shoulder became sculptured marble. The strange attendant creatures, with their fiery eyes and trailing vapors, busied themselves round his head. The body lifted a fraction of an inch from the sand and a bubble of air escaped from the mouth with a wet plop. Then it turned gently in the water. (176-177)