A series of recent discoveries made by a young team from the University of Toronto has finally solved a mystery that has puzzled scientists for more than a century, finding out what hyoliths actually are.

Hyoliths are marine creatures that lived 530 million years ago and their fossils are quite common. In spite of this, paleontologists were unable to give them a proper classification until now.

A Great Discovery

A team of Canadian researchers decided to find out the exact nature of hyoliths, which were speculated to be related to mollusks. The information that existed until this point seemed to support this theory as the cone-shaped animals look quite similar to our understanding of a "mollusk."

This hypothesis was, however, proven to be untrue by a series of extraordinary discoveries made in an area known as the Burgess Shale by the team of researchers.

Although hyolith fossils are found quite often, soft tissues were never recovered and thus many questions about the creatures could not be answered. The fossils discovered by the team, however, were preserved together with their soft tissues and as a result, their true nature was finally revealed. Hyoliths are not closely related to snails or squids but are actually related to brachiopods.

A Lesser Known Branch In The Tree Of Life

Brachiopods are a group of animals that belongs to a few surviving species; however, this is not always the situation, as there are many brachiopod fossils left as evidence of times when they used to flourish.

Brachiopods are different from mollusks in a few key areas. Their soft body is enclosed between an upper and a lower valve or shell, while bivalve mollusks have a left and a right valve. Brachiopods only open their valves in front to feed but otherwise keep them closed for protection. This was also revealed by the newly discovered hyolith fossils, which finally helped the researchers find the origin of the sea creatures, as described by Joseph Moysiuk, the leader of the team.

"Our most important and surprising discovery is the hyolith feeding structure, which is a row of flexible tentacles extending away from the mouth, contained within the cavity between the lower conical shell and upper cap-like shell. Only one group of living animals – the brachiopods – has a comparable feeding structure enclosed by a pair of valves," he noted.

Hyoliths had a rather peculiar aspect, which made their classification so difficult until this point. All of them had one elongated, cone-shaped shell, as well as a smaller, cap-shaped one.

Also, some species had some spines, which may have been used when the animal wanted to raise its body in order to eat. Hyoliths lived in the Cambrian seas, starting 542 years ago, going extinct about 252 million years ago.

So, 175 years after their discovery, scientists can finally close this chapter in the history of paleontological mysteries, also bringing a better understanding of the evolution of animals during the Cambrian era.