I don’t precisely know why I have a July 2003 KIDS DISCOVER Money magazine, but on page 5 I found this bit about cowrie shells:

Cowrie shells became a popular type of currency in Africa and India but were first used in China at least 3,500 years ago. The cowrie shell became the Chinese character for money. Cowrie shells are the longest-used currency in history, and as recently as the middle of the 1930s, they were still used as currency in some parts of West Africa.

Nothing here yet about widgets, but I’ll keep reading.