The choice of N. gibbosulus in Mediterranean web-sites and N. kraussianus is South African internet sites is really a functionality in their availability inside the vicinity of the web pages, but will not explain why this genus was chosen more than other shells of comparable sizing and form. A comparison https://medium.com/@spoilmevintagediy/the-rich-history-of-beadwork-a-journey-through-the-ages-4e4fd2e474cf