Construction workers have found the fossils of 550 million-year-old unknown invertebrate creatures in a temple renovation in eastern Anhui Province, a local government source said Friday.

The crimson worm-like fossil appeared on two pieces of sand stone, about 1.7 meters high and four meters and seven meters long respectively, when the workers were laying the foundation of the main hall in the Qinglong Temple of Fengtai County, according to the source.

Experts from the provincial museum confirmed the curved lines were fossils of some spineless creatures more than 550 million years ago, however, the exact species is still a mystery to them, according to the cultural office of Fengtai County.

Experts said these fossils offered direct evidence for the research on the origin and evolution of metazoan, or multicellular organisms.