The explanation of the origin of the outbreaks is still very controversial. Charles Birkland suggested that they were related to storms that could wash out nutrients from atolls, which stimulated phytoplankton grown, which, in turn, increased the survival of starfish planktotrophic larvae. Others have argued that larval starvation is not a limiting factor in larval survival. It was also argued that typhoons and other storms killed corals, causing starvation among the starfish and a switch to roving in aggregations in search of food. Pacific shallow reefs are often dominated by the the erect coral Pocillopora damicornis .
Coral reefs line the inner and outer parts of the island.
Darwin hypothesized that the earth's crust was slowly sinking, and that corals were growing upward and keeping up with the overal sinking rate. At first, a submarine volcano might be jutting out into the sea, but sinking led to the ring of coral reefs around the volcano to grow upwards and form the islands. While most agreed with this hypothesis, the geologist Harry Ladd confirmed it by leading a drilling team to this region. The team drilled through hundreds of meters of coral reef rock before reaching volcanic rock below of Eocene age. The arrow points to a clown fish, Amphiprion clarkii , one of many members of the fish family Pomacentridae.