Mystery shell on Ocracoke beach

Text and photos by Lynn Ingram

There it was.

At my feet.

An exquisite, perfectly intact shell, about the right size to be that Scotch bonnet that I so covet. Did I now possess my very own state shell of North Carolina?
Nope, ‘twas not a Scotch bonnet.

So, what was it?
With faith that my “Seashells of North America Guide to Field Identification” would lead me to a correct identification, I searched its pages, but I was disappointed in my inability to identify the shell.

More than a month later, I decided to ferret out the answer. Finally—and grudgingly—I resorted to the Google Lens function on my phone.

As if by magic, Google, with its infinite search capabilities, will identify the object for you.
Google identified my shell as Laevistrombus canarium, or dog conch, or Strombus canarium, a species of edible sea snail.

But there was a glaring problem: This sea snail with its creamy and spiraled shell doesn’t live here.
By “here” I don’t simply mean Ocracoke. I mean this ocean.

Dog conch is an Indo-Pacific species of sea snail, found from India and Sri Lanka to Melanesia, Australia and southern Japan.

How could this little sea snail have found its way from those far-flung places to Ocracoke?

I’d read in the Ocracoke Observer an account of the March meeting of the North Carolina Shell Club.

So, I emailed John Timmerman, a co-chair of the annual Shell Show.

“You identified the shell correctly,” he wrote. “Unfortunately, these shells make it onto the incorrect regional beaches via human activities. For example, when a wedding is held on a beach the organizers sometimes buy shells to scatter in the sand for added decor. Some of the shells get lost, and then an unsuspecting hunter such as yourself comes along.”

I wondered if there were other plausible explanations for how this Pacific Ocean creature turned up on Ocracoke.
Was there a celebration on some other beach where people cast shells carelessly about, not thinking of the conundrum those shells might one day produce for beachcombers?
Is there some little-known ocean current that periodically deposits Pacific Ocean shells on Atlantic Ocean shores?
Did a big fish eat it and bring it here? Or maybe some wandering seabird snapped it up and later spit it out?
My curiosity led me to people who know about such things as shells and oceans and currents.

Terri Kirby Hathaway, a 40-year-resident and beachcomber of the Outer Banks, worked as the marine education specialist for North Carolina Sea Grant for 18 years and also was education curator at the North Carolina Aquarium on Roanoke Island.
“It’s definitely not anything from around here,” she said of my shell.

I wondered aloud if the pretty polish on my shell might have alerted me to the possibility that it could have been a purchased shell.

Hathaway said that many found shells have exactly that kind of polish and perfection.

She herself has seen shells that lovely and smooth, “because when the animal is alive and moving about its body covers up the shell and kind of protects it…keeping it shiny.”

Hathaway said the polish “just means it might have been freshly dead or collected alive and killed.”

Hathaway quashed my notion about a big fish or a bird having brought my shell here. Had either creature eaten my shell, it would not have appeared as I found it, as both bird and fish would have subjected the shell to processes that would have rendered it not so smooth and pretty.
To my surprise, Hathaway said that it is possible that the shell was lost from some house that recently fell into the Atlantic Ocean, even from a house at Rodanthe.

I’d wondered about this and figured that was impossible, as that would require a current that runs north to south and then westward.
“The predominant longshore transport current along the North Carolina coast runs north to south, because waves approach the shore at an angle, setting up that movement down the shoreline,” Hathaway said. “To further complicate matters, that longshore movement can (also) be from south to north.”

Dr. Joe Montoya, director of Georgia Tech’s Ocean Science and Engineering Department, said that one possibility for this sea snail’s appearance on Ocracoke concerns the ballast tanks of oceangoing ships.

Ocean organisms like sea snails (and also sponges, crabs, sea stars, worms, and fishes) begin their lives as larvae that reside in plankton.

Drifting planktonic larvae gives some species a way to disperse; one of those ways is by getting caught up in the ballast water of ships and then accidentally traveling to parts of the ocean that are not their normal habitat.

Regulations regarding ballast water are intended to keep this from happening, Dr. Montoya said, as sometimes this could result in the accidental transportation of what might become an invasive species.

The appearance of Laevistrombus canarium at Ocracoke, said Dr. Montoya, is “an interesting mystery.”

Timmerman added further speculation.

Sometimes, when people are cleaning house, they might come upon a box of shells they no longer want.
“Rather than tossing such neat things in the trash, they scatter them on a local beach. “This works fine until the shells being scattered are from a different part of the world, and the next collector comes along and gets a head scratcher,” he said.
Timmerman said fossil shells can be seen along Devil Shoals Road opposite the NPS campground.

Those fossils, Timmerman said, are from a mine in Central Florida and other areas and were brought in as ballast for the dirt road.

“Road work is another way shells and fossils are moved well away from where they were found,” Timmerman said.  “Humans are great at moving objects around the planet, and when it comes to natural ones like shells, that can lead to unintended stories.”  
Indeed.

So, there will be no definitive answer to the question of how my Laevistrombus canarium appeared on the Ocracoke beach.

Perhaps that’s a better outcome than actually solving the mystery, as this one little shell initiated conversations about sea biology and the vagaries of human behavior and its fascinating consequences.

Lynn Ingram’s favorite things are words and oysters. She is owned by the world’s most perfect feline, Annabelle the Wonder Cat. A native of Cheraw, SC, she comes to Ocracoke to restore her soul and spirit.