Microscopic 570-million year old fossils that resemble soccer and baseballs found in China could be the oldest example of animal life found to date, according to a Tuesday report in Discovery News.

Scientists had previously figured the microscopic fossils found from the Doushantuo Formation in south China were gigantic sulfur bacteria. Researchers from the University of Bristol studied the fossils by comparing them to living and decayed Thiomargarita, a type of bacteria. The Doushantuo fossils and modern bacteria looked nothing alike, the comparison showed. With the bacteria theory cast out, scientists sought a different hypothesis to identify the baseball-looking fossils.

Shuhai Xiao, Virginia Tech geobiology professor who took images of the fossils, hypothesized that the fossils are metazoan embryos. Another theory contests this claim and proposes the fossils as protists, early unicellular organisms. Protists are not animals but they may have been the root from which all animals and plants developed from.

Philip Donoghue a University of Bristol paleobiology professor who was part of the investigating team, doesn't think the fossils represent the start of all animal life on the planet.

Although the site in China is a gold mine in terms of how many fossils were preserved there, it doesn't mean that the search for the earliest animal should end there. Two other animal fossils have been discovered at the site. One such animal named Vernanimalcula, meaning "small spring animal", has been called by Jun-Yuan Chen of the Nanjing Institute of Geology and Paleontology at the Chinese Academy of Science and some of his colleagues to be the first known bilateral animal or the first with body symmetry. Other scientists dispute that claim.

Other fossils found in the Flinders Ranges of South Australia is also contenders for the title of world's oldest animal. The fossils which represents a collection of circles, anvils, rings and wishbones were probably sponges. The fossils were found in rocks which were dated about 640-650 million years ago.

Additional research about the Doushantuo fossils is expected to be released in the journal Science in the future, according to Donoghue's web site.