An Ancient Penis Worm With Rings of Sharp Teeth Has Been Discovered in the Grand Canyon

About 500 million years ago, the Grand Canyon was a great sea, and among the creatures it harbored was a newly discovered type of penis worm, armed with many rings of teeth.

Penis worms are marine creatures with a distinctly phallic appearance. There are more than 20 known species living across the world’s oceans today, as well as a number of extinct ones, like this new discovery. The researcher who made the find was searching for fossils in the Grand Canyon and named the species Kraytdraco spectatus in honor of the huge burrowing krayt dragons that appear in the Star Wars universe. Details of the discovery were published in the journal Science Advances.

The authors believe that the worm fed using a retractible throat that could be pushed outward, inside out, before being drawn in on itself—like the finger of a glove being inverted. Lining this throat were rings and rings of teeth.

Trying to imagine how the ancient worm might have fed, the researchers hypothesize that along this proboscis it combined strong, sharp teeth with more delicate feathered ones for a two-stage eating process. The former could have been used to pick up food such as algae and microorganisms dispersed in the sand where the worm would have lived, the latter to filter this food out of the substrate and chew it. But having only a fossil to look at, and not being able to see the worm at work, this remains only a hypothesis.

An adult specimen would have measured about 15 to 20 centimeters long. This is much larger than the species of penis worm that survive today, which have undergone miniaturization over the millennia and now do not exceed 2 to 3 millimeters.

Although the phallic worm monopolized scientists’ attention with its teeth, fossils of other creatures were also found in the same expedition. They’re estimated to date from before the beginning of the Cambrian period, roughly 500 million years ago, considered by experts to be the dawn of complex animal life. These other creatures, early types of shrimp and mollusks, are valuable because they suggest what the world’s first predators looked like.