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

Along the shoreward edge of the shallows the advancing clearness was full of strange, moonbeam-bodied creatures with fiery eyes. Here and there a larger pebble clung to its own air and was covered with a coat of pearl. The tide swelled in over the rain-pitted sand and smoothed everything with a layer of silver. Now it touched the first of the stains that seeped from the broken body and the creatures made a moving patch of light as they gathered at the edge. (176)