Chinese geobiologists have unearthed mysterious spherical fossils that may be among the world's earliest animals.
The fossils, known as Megasphaera, came from a rock layer in southern China.
Measuring a mere 0.03 inches, these fossils were preserved for more than 600 million years in rock and are too complex and differentiated.
"The fossils may represent the transition between single-celled life and multicellular animals, said lead researcher Shuhai Xiao, a geobiologist at the Virginia Institute of Technology.
Researchers observed multiple cells, cleaved together in spherical clusters, in the lab.
The cells were different from one another in shape and size.
The paper was published in the journal Nature.
