The choice of N. gibbosulus in Mediterranean web sites and N. kraussianus is South African internet sites is often a function of their availability while in the vicinity of the internet sites, but would not describe why this genus was most well-liked over other shells of similar dimensions and shape. https://medium.com/@spoilmevintagediy/the-rich-history-of-beadwork-a-journey-through-the-ages-4e4fd2e474cf