The choice of N. gibbosulus in Mediterranean web pages and N. kraussianus is South African internet sites is actually a function in their availability while in the vicinity from the sites, but won't describe why this genus was favored in excess of other shells of similar size and shape. A https://medium.com/@spoilmevintagediy/the-rich-history-of-beadwork-a-journey-through-the-ages-4e4fd2e474cf