Fossils have been reported sporadically throughout the lower Cambrian Heatherdale Shale (Normanville Group), Fleurieu Peninsula, South Australia, but there has been little taxonomic documentation of faunas. Problematic cap -shaped fossils from the lower member of the formation originally attributed to Helcionella are herein formally described as a new genus and species, Tribelopoma amygdala gen. et sp. nov. The asymmetric valves with accretionary growth and probable calcium carbonate composition support a molluscan affinity, and comparisons with other enigmatic cap -shaped taxa suggest a possible helcionelloid affinity. Taphonomic processes related to early diagenesis provide evidence of a rigid shell, prone to brittle fracture during compaction.