I wrote an article before on the same concept you are trying to mention. https://hackernoon.com/are-we-about-to-redefine-money-again-4bed5344ebaa

Yes, sea shells, tally sticks, do not need to have a store of value to be a medium of exchange. The reason is due to "Community agreed barter". As long as there exist, people who treat it as a medium of exchange, it can be used as a medium of exchange. Please keep in mind tally sticks and seashells didn't suffer volatility issues hence could be adopted easily.