There are no conclusive theories about the formation of these coral atolls. The most accepted theory is given by the English Evolutionist Sir Charles Darwin. He concluded in 1842 that the subsidence of a volcanic island resulted in the formation of a fringing reef and the continual subsidence allowed this to grow upwards.

When the volcanic island became completely submerged the atoll was formed encircling the lagoon where, with the action of the wind, waves, reef to currents and temperature, the coral islands were formed.

Sand bags were first formed in an atoll. They became naturally the nesting grounds for sea birds. They continued to be their exclusive preserve till as a result of the fertilization of the soil by their droppings ( Guano deposits), ground vegetation became possible and man then took over, thus leaving the birds to seek another sanctuary.

fundamentally this concept is still valid, although many consider submerging volcanic islands is by the melting of Pleistocene ice sheets. The fringing reefs are quickly built, repaired and strengthened by a micro organism called polypous. The are the architects and engineers of these atolls. The corals are the hard calcareous skeleton of these polypous.