Measuring half-an-inch long, the fossil worm—named Wufengella and unearthed in China—was a stubby creature covered in a dense, regularly overlapping array of plates on its back, belonging to an extinct group of shelly organisms called tommotiids.

Surrounding the asymmetrical armor was a fleshy body with a series of flattened lobes projecting from the sides. Bundles of bristles emerged from the body in between the lobes and the armor. The many lobes, bundles of bristles and array of shells on the back are evidence that the worm was originally serialized or segmented, like an earthworm.

The findings are reported today in the journal Current Biology. Study co-author, Dr. Jakob Vinther from the University of Bristol's School of Earth Sciences, said, "It looks like the unlikely offspring between a bristle worm and a chiton mollusk. Interestingly, it belongs to neither of those groups."

The animal kingdom consists of more than 30 major body plans categorized as phyla. Each phylum harbors a set of features that set them apart from one another. Only a few features are shared across more than one group, which is a testament to the very fast rate of evolution during which these major groups of animals originated, called the Cambrian Explosion, about 550 million years ago.