Fig. 6

a Photo of R 2 in the field. R 2 mound is onlapped by oolite beds in the flank. The man as scale is 1.8 m in height; b A polished slab (Sample 29 in Fig. 2) shows that the aggregations of calcimicrobes building the frame are fan-shaped and were encrusted by sediments; c The close-up of rectangle area in (b). Renalcis (Rc) intergrew with Tarthinia (Tn), and normally the latter surrounded the former. Archaeocyaths (Ac) are not common in presence. The space between calcimicrobial aggregations is filled with silty/sandy micrite (M); d Photomicrograph (PPL) shows that Renalcis thalli are branching and chambered. The chamber varies in morphology from lunate, to equant, to reniform, to irregular. A few Epiphyton (Ep) thalli are in presence in the framework as well; e Photomicrograph (PPL) shows that some thalli have V-shaped clefts piercing their thick walls, and are Izhella, distinguished from Renalcis (Rc). Sample 30 in Fig. 2; f Photomicrograph (PPL) shows that Tarthinia (Tn) thallus is similar to Renalcis (Rc), but its wall (yellow arrow) is much thicker than the latter (red arrow), and characterized by vague inner surfaces. Sample 32 in Fig. 2; g Photomicrograph (PPL) of Metacyathellus lepidus (Yuan and Zhang). Sample 29 in Fig. 2; h Photomicrograph (PPL) of Erismacoscinus zunyiensis (Yuan). Sample 32 in Fig. 2