Eight islands have been developed as resorts; the remaining 57 islands are uninhabited. Baa Atoll, particularly its extensive coral reefs, harbours globally significant biodiversity including significant concentrations of whale sharks, manta rays and marine turtles, and also a unique diversity of benthic fauna, including rare pink hydrozoans corals (Distichopora nitida), Bryozoans (Bugula) and sea slugs (Tambja olivaria) that are only recorded from Baa atoll. Baa has a particularly high density of the ring-shaped reef forms called faroes, a peculiar reef structure unique to the Maldives, as well as other unique reef forms. Baa Atoll also has one of the largest areas of mangroves in the central part of the Maldivian atoll chain, and one of only two roosting sites in the Maldives for the frigate bird (more than 10,000 individuals).