Abstract:Three species and three genera of algal fossils in the Banded Manganese Formation (BMF) from Nantuo Formation, Xiangtan, Hunan Province, China, which is 720–830 My in age are described and named. All of the microfossils are interpreted as being the remains of bluegreen algae, and of these, one species Eoentophysalis xiangtanensis is new. The assemblage differs from most other Precambrian biotas so far described, it is dominated by coccoid algae, especially E. xiangtanensis. Analysis of the assemblage suggests that it was deposited in the subtidal and lower intertidal area, and that E. xiangtanensis is closely relative to the deposition of BMF. Possible biological origin of late Precambrian BMF, Xiangtan, is emphasized in this paper. The following are noteworthy: 1) E. xiangtanensis needed inorganic matter as its growing factors and the manganese (Mn++) in solution could be absorbed immediately and accumulated when it was alive; 2) Unmovable carboxyl group inside and outside of cells could accept the soluble manganes; 3) soluble manganese in water could be combined with the free oxygen yielded by photosynthesis and from photolytic disassociation of H2O; and 4) cell endoplasm could be replaced by manganese around it during the diagenesis after it was died.