St. Peter and St. Paul Islets are the only place on earth where the abyssal mantle rock is exposed in the surface, emerging from a depth of over 4000 meters. This small Equatorial Atlantic archipelago is located 1010 Km away from Natal and has a research field station maintained by the brazilian navy. Its isolation is believed to have prevented the settlement of many species but favoured endemism in the ones that made it, such as the locally abundant damselfish, Stegastes sanctipauli. The exposed rocks are populated by grapsid crabs, brown boobies and noddies. The rocky islets also attract a variety of pelagic fishes that are exploited by commercial fisheries, especially tuna.