Sponge–microbial boundstones, containing lithistid sponges (areal percentage, approximately 14%) and microbial components (areal percentage, approximately 39%). The sponges in this section are anthaspidellid demosponges. The microbial components consist mainly of frequently branched columnar stromatolites. Vacant spaces among frameworks formed by a combination of stromatolites and sponges are filled with lime mud and rare bioclasts, including trilobites, chancelloriid sclerites and sponge spicules.