WELLINGTON (AFP) - A unique colony of tens of millions of starfish-like creatures has been discovered on a mountain peak lying below the ocean in sub-Antarctic waters south of New Zealand, scientists said Monday. Tens of millions of brittlestars are estimated to inhabit the vast, flat-topped marine mountain colony, dubbed Brittlestar City by scientists, New Zealand's National Institute of Water and Atmospheric Research (NIWA) said. Scientists from New Zealand and Australia also collected some species never before recorded from the underwater peak known as a seamount on the Macquarie Ridge, which stretches 1,400 kilometres (870 miles) underwater from south of New Zealand to near the Antarctic Circle. They photographed hundreds of brown-black brittlestars on every square metre (yard), and estimate tens of millions of them populates the 100-square-kilometre (39-square-mile) flat top of the seamount. The brittlestars live arm-tip-to-arm-tip on the summit, 750 metres above the sea floor and 90 metres below the sea surface. Their arms wave in the current, catching food, which floats past on the circumpolar current, flowing at a rapid four kilometres an hour as it, forces its way between peaks in the Macquarie Ridge. "We were excited to see such a huge assemblage of brittlestars on the Macquarie Ridge seamount," said ecologist Dr Ashley Rowden of the NIWA. He described the vast colony of brittlestars as amazing and said it would make a significant contribution to understanding life found on seamounts. Corals and sponges are usually the dominant life forms on seamount peaks, filtering food that arrives on the current. Biologists on the believed "Brittlestar City" were the first ever find of its kind on a seamount, attributing the unique discovery to the unusually flat shape of the peak and the rapid current. "This current is estimated to be 110 to 150 times larger than all the water flowing in all the rivers of the world," said Mike Williams of NIWA. "In terms of the world's oceans, New Zealand sits right beside the motorway." The discovery was made during a month-long expedition on NIWA's research ship in April. It is part of a study of seamounts being done as part of the Census of Marine Life, an ambitious global survey to document the life of the world's oceans.