Country diary: Pearls of the ocean that might just return to British shores | Mark Cocker

Holkham, Norfolk: A local company is attempting to revive not just European flat oysters, but a whole wealth of species on a nearby seabedIt sits on my desk as I write, a memento from our Norfolk visit, where I found it at the tide’s edge. This blue-and-ochre shell comprises 30 or more fine layers of wavy calcium, rising to a swollen weathered apex. You could imagine the original bivalve sitting in your palm as an intact and living whole. But for that thought experiment to be true, I&rsquo