A penis worm that lived during the Cambrian period has been discovered by scientists creating a new database. The carnivorous beast lived half a billion years ago, long before the age of dinosaurs.

Several varieties of penis worms — both extinct and contemporary — are known to scientists, and the largest of the marine species can grow to be more than 15 inches in length. The animals are equipped with a proboscis featuring spines, hooks and teeth, for piercing and holding prey. Penis worms flourished around 500 million years ago, during the Cambrian period. At that point in time, they were among the most common species on the planet.

When hunting or defending itself, members of this type were able to turn their throats inside out, baring the network of teeth that lay inside. The display could also resemble a trunk or human male appendage.  

Careful examination of the patterns of teeth in penis worms allowed the creation of a new database for biologists as well as the discovery of a previously unknown variety of the animal.

"Taken together, our study has allowed us to compile a 'dentist's handbook' that will help paleontologists recognize a range of early teeth preserved in the fossil record," Martin Smith of the University of Cambridge said.

Researchers utilized microscopes to study these tiny teeth, each only about 1/25th of an inch across. The body parts were found to have prickles and hairs covering segments of a base of scales.

"[T]he specimens from the Lower Walcott Quarry had some teeth with a central prong that was flanked by just two skinny, hollow 'denticles,' whereas up to eight denticles were common in the corresponding teeth of the Upper Walcott Quarry specimens," Megan Gannon wrote for Live Science.

Ottoia prolifica were discovered in 1911 by paleontologist Charles Walcott, in the Burgess Shale of Canada, a region rich in fossils dating from the Cambrian period.

The creature lived in burrows, and may have even eaten other penis worms, along with shelled prey and mud. Analysis of tooth marks left behind in mud provided evidence of the newly recognized species of the creatures.

Around the world today, Priapulida, the scientific name for the worms, live in mud, and can be found in waters up to 300 feet deep. Just 16 species of the animal are known to exist globally, a small fraction the number present during their ancient reign.

Creation of the "dentist's handbook" for varieties of penis worms and discovery of the new species was detailed in the journal Palaeontology.