The reef flat extends from the inner part of the reef crest and rubble zone to the beach. At low tide the majority of the region is covered in shallow water (usually less than a metre) that is contiguous with deeper lagoonal water but separate from the oceanic water below the level of the reef crest. This region is divided into two zones. The inner or sandy zone lies closest to the island and is typified by expanses of sand with small patches of living coral, often forming micro-atolls, and dead coral rubble colonised with coralline and fleshy algae. A range of coral genera can be found in this zone and a variety of sea cucumbers are conspicuous. A wide diversity of invertebrates are associated with the rubble and algal patches, living on, within and under these substrata. Inspection of these substrata under a microscope reveals further invertebrate diversity. This area also has a diverse and complex meiofaunal community