CAMBRIDGE, Mass., May 6 (UPI) -- It's probably too late for the unfortunately named penis worm to request new nomenclature. The ancient Cambrian worm has been extinct for nearly 500 million years, and it's already plastered all over the Internet.
But the worm is more than just a trigger for grade-school giggles. A newly discovered penis worm fossil -- and its uniquely toothed mouth and throat -- is helping scientists create a sort of "dentists' handbook" that could aid in the differentiation and categorization of other ancient worms.
In addition to its phallic shape, the penis worm's mouth and throat were beset with a hideous set of teeth -- a sort of cross between the fictional sarlacc creature of Star Wars and a cheese grater. Even more frightening, the worm had the ability to turn its mouth inside out and drag itself along the ground using its tooth-lined throat.
Scientists at the University of Cambridge, in England, recently used electron microscopy to scan and model the insides of a penis worm fossil collected from the shale deposits of Western Canada.
Researchers believe they'll be able to better differentiate between ancient species of worms by using teeth structure as a sort of reference key. There are 16 species of extant penis worms, and likely more yet to be discovered. The Latin name of the variety described in the latest study is Ottoia prolifica.
"As teeth are the most hardy and resilient parts of animals, they are much more common as fossils than whole soft-bodied specimens," lead study author Martin Smith, a postdoctoral researcher in Earth sciences at Cambridge, said in a press release.
"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," Smith explained. "Now that we understand the structure of these tiny fossils, we are much better placed to [identify] a wide suite of enigmatic fossils."
Modern penis worms are hard to find. Most have been pushed into extreme underwater environments. But during the Cambrian period, they were a top predator -- ferocious and devouring all comers.
The new study was published this week in the journal Paleontology.