 The reef primarily owes its existence to its depth, as it is below the freshwater layer of discharge from the Amazon into the Atlantic Ocean, a discharge that represents one fifth of the outflow into the Earth's oceans.The majority of the reef is made up of beds of rhodolith, various species of red algae, which superficially resemble coral.While it has been described as "impoverished", and "not having the biodiversity of some of the more prominent coral reefs of the world", 61 species of sponge and 73 species of fish, in addition to various coral and starfish species, have so far been identified as inhabiting the reef, including staghorn corals, and spiny lobsters.