VOL.35 NO.2 OCTOBER 2OO5 - British Shell Collectors' Club

Page 6 PALLIDULA
A Twelfth Century Cowry
by Julian Joseph
Introduction
The base of a cowry shell was found in a 12 th – 14 th century archaeological site near Cambridge. There was
also a fragment of cowry shell, and a piece of an oyster shell which it has not been possible to identify.
The feature from which the shell came contained a partial human skeleton. The individual was estimated to be
approximately 15 years old at time of death, but the sex of the remains could not be determined. Some of the
bones were missing and were described as disarticulated when recovered, suggesting that this was a reburial.
In addition to the shells, a spindle whorl, a pierced coin and a bead were found in the feature.
The company responsible for investigating the site, Archaeological Solutions, asked the BSCC to find someone
to write a report about the cowry fragment. The following is the result.
A brief overview of the cowries
The cowries are a group of approximately 230 living species of marine gastropod molluscs. They belong to the
superfamily Cypraeacea, which includes 3 main families: Ovulidae (egg shells) Triviidae (includes the British
“cowries”) and Cypraeidae (the “true” cowries). The family has a worldwide distribution between the latitudes of
approximately 40° north and 40° south. The majority of species inhabit warm, shallow water in the Pacific and
Indian Oceans; there are a few species in the Caribbean Sea, and a number of species in the cooler waters of
the Mediterranean, southern Africa and southern Australia.
The shell
The shell of a cowry is typically domed, with a flat base and almost bilaterally symmetrical. It is usually solid and
glossy, and often very colourful. They range in size from approximately 10-150mm., depending on the species.
The spire, usually prominent in gastropod shells, is small and completely, or almost completely hidden in adult
specimens of most species. The aperture is reduced to a narrow slit, usually with teeth along both edges.
Like all shells, that of a cowry is made of a combination of needle-like crystals of calcite and aragonite (both
forms of calcium carbonate) and a fibrous protein component. In cowries, the crystals are arranged in layers,
with crystals in different layers aligned in different directions, thus preventing fractures from spreading across
the shell when it is stressed. The protein surrounds the crystals, giving extra strength. The outermost layer is
usually highly polished.
Shell terminology
The following diagram shows the parts of a cowry shell as viewed from the base: