The spur and groove structures on the seaward side of Peros Banhos.  These spurs are constructed of calcareous red algae, mainly of the genus Porolithon.  Spurs are 1-2 m high and spaced 1-2 m.  They extend 30 - 70 m to seaward, where they dip along the deepening reef slope.  Photo is taken on the algal ridge, which is made of the same material, and which links the spurs.  It is crucial to resisting erosion from the breaking waves.
