Most Intriguing Organ of the 'Penis Worm' Excites Scientists

Researchers at Cambridge University have studied the dental structure of the penis worm to identify previously unknown species dating from the Cambrian.

The penis worm has existed since 500 million years. Besides its phallic appearance, its teeth are noteworthy. The worm can turn its mouth inside out and use its teeth as hooks to grip surfaces for movement. Through their study of a specific species of penis worm fossils found in the Burgess Shale site in Canada, researchers developed a handbook that has helped them identify several species of the worm from across the world.

"As teeth are the hardy and resilient parts of animals, they are much more common as fossils than whole soft-bodied specimens. But when these teeth - which are only about a millimeter long - are found, they are easily misidentified as algal spores, rather than as parts of animals. Now that we understand the structure of these tiny fossils, we are much better placed to a wide suite of enigmatic fossils," said Martin Smith, the paper's lead author.

Researcher studied a species of penis worm called Ottoia from the Burgess Shale site brimming with fossils from the Cambrian period to develop their dental handbook.

Teeth hold all sorts of clues, both in modern animals and in fossils," said Smith. "It's entirely possible that unrecognized species await discovery in existing fossil collections, just because we haven't been looking closely enough at their teeth, or in the right way," Smith said.