By Oscar Holland, CNN (CNN) — In an age when clocks are found in most pockets and on every screen, watchmaker Col&MacArthur’s selling point is not just time, but history itself. Known for using unconventional materials — from Pearl Harbor seawater to meteorite moondust — in the name of horological storytelling, the brand is now commemorating the D-Day landings with a series of watches made from US soldiers’ helmets and haversacks, as well as san…