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The mystery of clams in Japan



Shells are the first known form of legal tender in the world and have been used as such until the 1800's. The importance of shell money is clearly evident in daily life here in Japan where most if not all of the characters concerning money have imbedded in them the character of shell (貝). Goods (財), Savings (貯), buying (買), valuables (貨), Gifts (贈), Gambling (賭) are only a few such examples. The shell that was used here in the east was always the cowrie shell aptly named the treasure shell 宝貝 in Chinese/Japanese.


In North America, the Iroqoui and Algonquin tribes were famous for their wampum. Quahogs "Mercenaria mercenaria" (latin word for commerce) were the shell of choice in creating wampum. You can read this article in the Beachcombing Magazine to learn more.


It was surprising to me that I could find the same purple shells on my local beaches. This is because as far as I was concerned, quahogs were only found near New England.


So I did some "digging". Quahogs are also called hard clams. The beaches I walk are known for a shell called Hamaguri which is also called Asian Hard Clam (Meretrix lusoria).

They have the exact same combination of purple and white as quahogs do. In Asia, the white part is used to create pieces for the ancient board game Go. Yet Hamaguri tend to be half the size of quahogs. I was suspicious whether I was seeing only Hamaguri or if I was truly coming across quahogs as well.




A little more searching online led me to see that we do in fact have quahogs in Japan. They were first found in 1998 on an artificial beach in Makuhari, Chiba Prefecture. It is believed that they crossed the Pacific as stowaways in cargo ships.


Sawada Youichi, an asari clam (Manila Clams)fisherman in Ichikawa, first came across these large shells whilst sorting his catch. He had not seen them before so he took them to the Chiba Prefectural Fisheries Research Center where they were identified as Mercenari mercenaria. The Japanese name for them is Honbinosugai.


Sawada began commercial quahog fishing in 2005. He finds the clams at a depth of around 2 meters. Similarly to digging for Hamaguri clams, he uses a clam rake with a large steel basket that is attached to it. It is lowered from the boat and digs around in the sand and then the rake drags along the sand bed.


It took some time for these clams to be accepted by the public but over the time and with the help of a PR campaign in the Funabashi Fish Market, people have begun to enjoy eating the clams. Funabashi restaurants have even started to feature the quahogs as "local specialty". In 2017, Chiba Prefecture officially labelled the so called clams as a "Chiba brand marine product". You can read more about it here.


However, I was not quite satisfied with what I was finding, so I called Endosan, our local fisherman and uncle. He said the clams that were purple inside use to be sold to the aquarium to feed otters. He despairingly called them Baka Asari which translates to "Idiot Clams" because they are gigantic in comparison to to asari. With a little more sleuthing we found out that they are called saxidomus purpurata which Japanese call uchimurasaki which translates to "purple inside".


Mystery solved! It is uchimurasaki that I am finding!


But regardless of the name of these clams, these smooth pieces are beautiful and look lovely as decoration in the home or as jewelry. Here are a few examples. Let me know in the comments below how you use these.









Find shards in the shop here and/or artwork here.

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1 Comment


Wampum in New England (like you said) is pretty much found everywhere. My favorite, due to their color.💜 'idiot clams'.. that's pretty funny!! 🚫🤓🐚lol. I haven't been to the beach in a year or so, but they're the first thing I look for, depending on the area. A few summers ago, I was working to Dremel them, not an easy task,but got one half finished.

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