The rich volcanic soils on the islands foster the growth of a profuse vegetation. Beyond the coastal zones, where mangroves predominate, there are coconut palms, mangoes, and bananas, and above them is a forest zone, with many varieties of tropical hardwoods. Broom, lichens, and heather grow on the highest peaks. The animal life is similar to that found on Madagascar. Comorian waters harbor the coelacanth, a rare primitive fish once thought to have been extinct for 70 million years. Fossil remains of the coelacanth dating back 400 million years have been found.