Fig. 5

a Field photograph showing the largest reef in the assemblage 7 which contains stromatolites and serpulids. Above the reef is laminated fine tuffite; b Domal stromatolites showing that bright layers and dark layers are interlayered; c Colonial serpulid tubes are surrounded by microbes to form a small reef; d Microbial reef without serpulid tubes. Person in a is 1.7 m tall; Pens in b–d are 14 cm long for scale