The choice of N. gibbosulus in Mediterranean sites and N. kraussianus is South African sites is a function in their availability in the vicinity of your web pages, but won't clarify why this genus was most popular in excess of other shells of similar sizing and form. A comparison of https://medium.com/@spoilmevintagediy/the-rich-history-of-beadwork-a-journey-through-the-ages-4e4fd2e474cf