They are called stromatolite .

被称为“叠层石”。

Walter says the findings are consistent with previous research into 2.7 billion year old stromatolite fossils from the pilbara region of western australia conducted by his team .

walter说这项研究与先前他自己的小组在西澳大利亚的pilbara地区对于27亿年前的叠层化石的研究是一致的。