For years foresters and scientists have studied the rings found in treetrunks to determine the age of the growths. In a similar fashion, scientists are now scrutinising the rings lining coral skeletons. Since 1993, a team of Malaysian scientists have been cutting up corals,looking for traces of heavy metals. They hope the corals will reveal data on the extent of marine pollution. According to Dr Almah Awaluddin of Universiti Kebangsaan Malaysia (UKM), because corals feed by filtering food from water, whatever is found in the sea eventually accumulates in the coral skeleton.