The choice of N. gibbosulus in Mediterranean web-sites and N. kraussianus is South African web-sites can be a operate of their availability inside the vicinity with the web pages, but does not make clear why this genus was chosen above other shells of comparable dimension and condition. A comparison in https://medium.com/@spoilmevintagediy/the-rich-history-of-beadwork-a-journey-through-the-ages-4e4fd2e474cf