Suppose after the semester ends, you take a trip to an Island of Vieques. Upon arriving at the island, you make a stop at one of the markets and notice that everyone is carrying around jars full of cowry shells. You also notice the person in line in front of you just paid for a twelve-pack old Milwaukee beer with 8 cowry shells. Someone else just bought a Whopper Pizza Combo for 6 cowry shells. Thinking back to your economics class (as painful as that may be), you would conclude that a) this is a barter economy.
b) those cowry shells are serving as money.
c) cowry shells are valueless.
d) cowry shells soup is a delicacy.