The Rarest Seashell in the World

We all have some special finds in our beachcombing collections, and conchologists are especially proud when they are able to add rare specimens to their seashell collections. Imagine having a shell in your collection of which there are only a few known specimens in the world. Find a Sphaerocypraea incomparabilis shell and you can retire from shelling!

The Sphaerocypraea incomparabilis is considered the rarest seashell today. This snail shell is dark, golden brown with a row of zipper-like white teeth along the shell opening, It is part of the Eocypraeidae family of large sea snails, in the superfamily Cypraeoidea, which includes cowries. Until these shells were announced as a new species in the 1990s, the Eocypraeidae family was thought to have been extinct for 20 million years. Not only was this shell rare, discovering it was like finding a living fossil.

In the 1960s, there was a significant Soviet naval presence in the Gulf of Aden (located between the Arabian Peninsula and Africa, with Yemen to the north and the Arabian Sea to the east). In 1963, the first known shell of what is now known as Sphaerocypraea incomparabilis was dredged up by a Soviet trawler there. A few more specimens were found over the following decades, but they remained hidden in private shell collections in the Soviet Union for years.

In 1990, a shell dealer from Florida named Donald Dan heard rumors of a previously unknown shell now in several Russian collections. He eventually tracked down one owner and managed to purchase a Sphaerocypraea incomparabilis shell. He then purchased the shell found in 1963 by the Soviet trawler, and was able to see another belonging to a Soviet oceanographer who eventually sold Dan his specimen. Dan sold two of his shells to a private collector who eventually donated the shells to the American Museum of Natural History. Most of the known specimens are now in museums.



The American Museum of Natural History hired Martin Gill to appraise their collection in the early 1990s, and in 1997 a curator found that one of the shells was missing. It was eventually found and the theft was traced back to Gill, who had sold it to a Belgian collector for $12,000, who subsequently sold it to a collector in Indonesia for $20,000.

The snails that create these shells are thought to dwell deep in the waters of the northwestern Indian Ocean and the Gulf of Aden off Somalia. The depth of their habitat—and the dangers modern-day pirates in that region pose to those who would seek to collect them—have kept the known number of these shells to under a dozen. The exact location of the habitat is not yet known. Once it is found, you can expect Sphaerocypraea incomparabilis shells to drop in value like Conus gloriamaris shells, which were once the most rare and expensive shells in the world until the discovery of their habitat in 1969.

Photo credits, top to bottom: Gilles Mermet, hyotographics, Manuel Caballer.

This article appeared in the Beachcombing Magazine November/December 2021 issue.

Learn more about seashells

Learn more about identifying shells, the history of seashell collecting, great shelling beaches, and the lives of the animals who make the shells we find on the beach. Articles ›

No live shelling: Be sure shells are empty and sand dollars, sea stars, and sea urchins are no longer alive before you bring them home.