The thrombolitic mounds are domes up to 100 cm high and 40–60 cm wide embedded within within lime mud and shale (ribbon rock). Analysis of slabs revealed that the mounds consist of cm-scale thrombolitic “clots” and homogeneous micrite with several intraclasts and bioclasts filling the interclot spaces.
Two types of clots are recognised: keratolite–microbialite and lithistid sponge–microstromatolite clots. Keratose and lithistid sponges rarely occur together in the Mungok reefs.