The Use of Cacão Beans as Currency

Submitted by Ron Catterall.  This is an example of the sort of comment that form a 'topic'.  I'm not at all sure just how serious this discussion of currency is.

Many people have referred to the use of Cacão beans as currency, and indeed there are illustrations showing (apparently) sacks of something that might be beans in a position that might be a 'point of sale'.  Some points that occur to me: