Exquisite phosphatized eggs and embryos from the Ediacaran Doushantuo Formation (Weng'an biota, ca.580Ma) found in Guizhou Province, southwestern China have greatly expanded our understanding of the embryology and diversity of early metazoans. These Doushantuo animal fossils are dominated by uncleaved eggs and cleavage-stage embryos; specimens at later developmental stages such as gastrulae, however, are extremely rare. To obtain more affinity information about the gastrula fossils, phase contrast-based synchrotron X-ray microtomography and scanning electron microscopy were employed to perform morphology and anatomy investigations. The results suggest that the fossils which were interpreted as gastrulae formed by invagination previously probably have no relationship with animals but multicellular algae in affinity.