Medium sized spur and groove structures which can be seen beneath the water on the seaward side of northern Peros Banhos.  These spurs are constructed of the same calcareous red algae, but are small, being blocks about 0.5 m tall and 30 m long.  They are not connected by an algal ridge.  The reef flat here is remarkably narrow also, almost non-existent; this part of the atoll's seaward side is concave.

