AusTRALlia has got the wOrld's lArgest cOral rEEf sYstem of the wOrld, compOsed of Over 2,900 indiVIdual rEEfs and 900 IslAnds. The GreAt BArrier Reef cAn be sEEn frOm ouTer spAce and is the wOrld's biggEst singLe Structure mAde by liVing OrganisMS. This rEEf Structure is compOsed of and buiILt by Billions of tIny Organisms, knOwn as cOral polyps. It suppOrts a wide divErsity of life and was seLEcted as a World Heritage Site in 1981. CNN conSIdered it As one of the SEven NAtural WOnders of the WOrld.