What I took from the article is that it was both, but that it started with paying back debts, and markets occured shortly because of that. So you get 100 shells

What I took from the article is that it was both, but that it started with paying back debts, and markets occured shortly because of that. So you get 100 shells for the debt of your daughter to a neighbour, now what will you do with these shells? Find stuff to buy. To me it seems like it's almost instantaneous, but you could imagine that there would be a period of time where the 100 shells couldn't be traded, they were there to represent the debt of the bride, which would be paid pack like any debt.