Shell buttons

Visited the Heart of Hawick in the border town today with the U3A Museums group. In the section on the history of the weaving industry in the town, there was this shell, showing how shell buttons were made. I had no idea!
Not technically great (thick glass, low light, no flash) but I like the shape of the buttons above the shell.
(BTW shell or mother or pearl buttons always feel cold to the touch, unlike the artificial imitations!)