Tribal Taupe Sort-Of Rectangle, Stone or Shell? 5/16" x 11/16", Pack of 39 Buttons #23-130

Sleek and smooth, almost shiny, like polished stone. We were told they're shell, but it can be hard to get shell to be so perfectly flat, and they may be a little heavier than shell in our opinion. Mostly shades of warm light taupe, some mostly solid and many with natural stone-like patterning. Durable; not at all thin or delicate, one of a kind, semi-shiny, sleek, natural and beautiful. Most are about 5/16" x 11/16".  About 3mm thick. 1.5mm holes. Limited Supply. Vintage?  More questions than answers.  You'll get the exact 39 shown. They're nicer than the photos if you like unique and natural.