A new, previously unidentified creature has apparently been discovered by scientists from the United States studying fossilized embryos in China.

James Schiffbauer, assistant professor of geological sciences in the University of Missouri's College of Arts and Science, and a team of colleagues happened upon their discovery while studying fossilized embryos from the lower Cambrian Shuijingtuo Formation in the Hubei Province of South China.

The Cambrian Period, which occurred between 540 million and 485 million years ago, was a time when many of the wide variety of marine invertebrates first appeared in the fossil record, a university new release indicated.

Also called the "Cambrian explosion," fossilized records suggest it was a period during which the world's ecosystems rapidly changed and diversified.

Most discovered fossils from that period general reveal only the skeletal structure of organisms, which scientists explain may or may not be able to provide them with accurate models of prehistoric life.

"Before the Ediacaran and Cambrian Periods, organisms were unicellular and simple," said Schiffbauer. "The Cambrian Period ... ushered in the advent of shells. Over time, shells and exoskeletons can be fossilized, giving scientists clues into how organisms existed millions of years ago. This adaptation provided protection and structural integrity for organisms. My work focuses on those harder-to-find, soft-tissue organisms that weren't preserved quite as easily and aren't quite as plentiful."

Something obviously "went wrong" with the way the remains his team found were fossilized, Schiffbauer said.

"Our Earth has a pretty good way of cleaning up after things die. Here, the cells' self-destructive mechanisms didn't happen, and these soft tissues could be preserved," he said. "While studying the fossils we collected, we found over 140 spherically shaped fossils, some of which include features that are reminiscent of division stage embryos, essentially frozen in time."

The fossilized embryos the researchers found were notably smaller than other fossil embryos from the same time period, indicating new, previously unknown species, Schiffbauer explained.

Schiffbauer says additional research will focus on identifying the exact creatures the embryo remains belong to, and also where they existed in the planet's master evolutionary timeline.