''Caveasphaera'' is a

multicellular organism A multicellular organism is an organism that consists of more than one cell (biology), cell, unlike unicellular organisms. All species of animals, Embryophyte, land plants and most fungi are multicellular, as are many algae, whereas a few organism ...

found in 609-million-year-old rocks laid down during the

Ediacaran The Ediacaran ( ) is a geological period of the Neoproterozoic geologic era, Era that spans 96 million years from the end of the Cryogenian Period at 635 Million years ago, Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last ...

period in the

Guizhou Province ) , image_skyline = , image_caption = , image_map = Guizhou in China (+all claims hatched).svg , mapsize = 275px , map_alt = Map showing the location of Guizhou Province , map_caption = Map s ...

South China South China ( zh, s=, p=Huá'nán, j=jyut6 naam4) is a geographical and cultural region that covers the southernmost part of China. Its precise meaning varies with context. A notable feature of South China in comparison to the rest of China is ...

. The organism is not easily defined as an

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

or non-animal. The organism is notable due to the study of related

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

nic

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s (measuring about a half-millimeter in diameter) which display different stages of its development: from early single-cell stages to later multicellular stages. Such fossil studies present the earliest evidence of an essential step in animal evolution – the ability to develop distinct tissue layers and organs. According to researchers, fossil studies of ''Caveasphaera'' have suggested that animal-like embryonic development arose much earlier than the oldest clearly defined animal fossils and may be consistent with studies suggesting that animal evolution may have begun about 750 million years ago. Nonetheless, ''Caveasphaera'' fossils may look similar to

starfish Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to ...

and

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

embryos. Still, researchers have concluded, "Parental investment in the embryonic development of ''Caveasphaera'' and co-occurring '' Tianzhushania'' and '' Spiralicellula'', as well as delayed onset of later development, may reflect an adaptation to the heterogeneous nature of the early

nearshore marine environments in which early animals evolved."

References

{{Taxonbar, from=Q85751043 Enigmatic eukaryote taxa Tree of life (biology)