error of first paragraph
it did not start with seashells
it started with goods barter
1 caveman axe for 1 cavemans daughter of adequate age
then
10 loaves of bread for 1 horse shoe
sea shells were not a currency used at the coast because seashells were abundant
it was not a world wide trade thing and was not something that was wid spread. basically sea shells were only used by certain clans (villages)
however.. where barter did turn into 'coin' was done here
Asian Cutlery
Sometime around 1,100 B.C., the Chinese moved from using actual tools and weapons as a medium of exchange to using miniature replicas of the same tools cast in bronze. Nobody wants to reach into their pocket and impale their hand on a sharp arrow so, over time, these tiny daggers, spades and hoes were abandoned for the less prickly shape of a circle, which became some of the first coins. Although China was the first country to use recognizable coins, the first minted coins were created not too far away in Lydia (now western Turkey).
Read more: The History Of Money: From Barter To Banknotes
https://www.investopedia.com/articles/07/roots_of_money.asp#ixzz5EB5krSDc