New species of gigantic, toothy worm identified in Canadian fossil collection

Researchers have discovered a new species of an ancient worm that was more than a metre long and had powerful jaws and teeth with which to catch its prey.

400-million-year-old fossil specimen has been in Royal Ontario Museum collection since 1994

The 400-million-year-old fossil of a species of worm called Websteroprion armstrongi had been in a collection at the Royal Ontario Museum in Toronto since 1994 but has only recently been closely studied. (Luke Parry)

Scientists have discovered a new species of a gigantic prehistoric worm.

This new species, called Websteroprion armstrongi — named after bassist Alex Webster of the death metal band Cannibal Corpse — is closely related to earthworms and leeches. 

The worm was studied by researchers from the University of Bristol, Lund University in Sweden and the Royal Ontario Museum in Toronto. The specimen was found southeast of Moosonee, Ont., in the Hudson Bay basin in 1994 and had been in the ROM's collection since then but hadn't been closely studied until recently. 

Their findings were reported in the journal Scientific Reports.

It is a very mean worm.- Sebastian Kvist, Royal Ontario Museum

Websteroprion armstrongi, which belongs to the Eunicida family, is like something out of a science fiction film. Measuring between one to two metres, it would burrow deep under the sediment of the ocean floor. But you'd hardly notice it: the only thing remaining above ground were its jaws, waiting for unsuspecting prey.

An artistic reconstruction showing the wide jaws of the W. armstrongi worm about to clamp down on a fish in the Devonian period. (James Ormiston)

While it was a very long worm, its jaw structure was a mere one centimetre in length. However, it is the longest jaw ever recorded for the species.

"It's a very long and slender worm," said Sebastion Kvist, curator of invertebrates at the ROM. "So, a centimetre is actually quite big for jaws. Normally, the jaws that they find in bedrock are only a couple of millimetres."

The jaws spread out perpendicular to the body and then snap shut. The worm then pulls its meal down into the burrow. 

"It is a very mean worm," Kvist said. 

There are worms around today that resemble the Websteroprion armstrongi  (see video below).

But this specimen is the oldest example of the species found so far.

The finding is a significant for understanding the early history of our planet.

"It's the oldest fossil of we know of this particular family," Kvist said. "The finding extends the range of time that these organisms have been present on Earth, and it allows us to better understand the ecology that was present at this age."

These "Bobbitt worms," as the Eunicida worms are informally called in a cheeky nod to Lorena Bobbitt, a U.S. woman who cut off her husband's penis while he slept in 1993, are found in warmer ocean waters in the Indo-Pacific region and in parts of the Atlantic Ocean.

In many regions, they are used as bait, and in the Pacific Islands, they are considered a delicacy to be eaten.


Nicole Mortillaro

Senior reporter, science

Based in Toronto, Nicole covers all things science for CBC News. As an amateur astronomer, Nicole can be found looking up at the night sky appreciating the marvels of our universe. She is the editor of the Journal of the Royal Astronomical Society of Canada and the author of several books. In 2021, she won the Kavli Science Journalism Award from the American Association for the Advancement of Science for a Quirks and Quarks audio special on the history and future of Black people in science. You can send her story ideas at