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Physical Feature: Coral rubble islets

Coral-rubble islet at Pearl and Hermes Atoll.
Coral-rubble islet at Pearl and Hermes Atoll. Photo Credit: James Watt

In atoll environments coral fragments and sand are distributed by currents and wave energy and pile up to create coral-rubble islets (moku liʻiliʻi). These islets typically form along the reef crest, or outer edge of the atoll, between the fore reef (ocean facing) and back reef (facing the lagoon). They can also form on shallow areas inside the atoll. The small, ephemeral land areas provide important breeding and nesting areas for green turtles and seabirds. They also provide haul out areas for monk seals where they can escape from predators, rest, molt, and give birth. As current patterns change within the atoll, and sea levels change, these islets can move around, and sometimes disappear. At French Frigate Shoals one islet is named Disappearing Island due to this characteristic.