Archaeocyath bafflestones with abundant cement. Renalcis also abundant.
Regularis Zone, Tortuosa Subzone.
Discrete mounds.
Renalcis-rich mounds with archaeocyaths in vicinity.

Abstract of ref. 1830:
With the possible exception of some older aggregations of  tubicolous skeletal forms, bioherms in. the Pestrotsvet Formation (Tommotian) of the southeastern Siberian Platform represent Earth's earliest metazoan-mediated reefs. They are certainly the earliest known bioconstructions of metazoan-calcimicrobial type. The bioherms are geographically limited to the transitional facies tract of the Siberian Platform, 
  separating restricted lagoonal from deep ramp and slope sediments.
Bioherms are intergrowths of archaeocyaths, calcimicrobes (Renalcis) and rare coralomorphs (Cysticyathus) in lime
mudstone which was cemented early on the sea poor. They consist of meter-scale mounds occurring either singly or stacked together.
Mounds can be categorized into component domains occupied by associations of lime mud, archaeocyaths, calcimicrobes and 
  cement. Some mounds are simply a conglomeration of such domains, with no discernible pattern of internal distribution, while 
  others possibly show incipient ecological succession. The calcimicrobe Renalcis was the major bioconstructor; it and the 
  synsedimentary cement were the principal contributors to framework construction. Archaeocyaths of themselves rarely 
  produced a framework, except where stereoplasm was abundant. 
  Nevertheless, the archaeocyaths provided substrates for the Renalcis and cement, and facilitated the development of
internal cavities.
  Archaeocyaths appeared, as bioconstructors, in the basal Tommotian sunnaginicus Zone. In the succeeding regularis Zone and thereafter, they flourished throughout the mounds, in some cases forming thickets of large sticklike cups atop mature mounds.
The bioconstructional regime established in these Tommotian bioherms prevailed throughout the Early Cambrian reef-building phase, particularly in argillaceous limestone facies. Likewise, the trophic web of this very early Cambrian community remained a  blueprint for shallow wafer, open, marine habitats throughout the epoch.