This past summer, I spent a morning hunting for shrimp and prawns on a remote beach in Scotland. It was the kind of ritual interaction with nature that modern people have long prized: wading through tidal pools at the edge of a rough ocean, I felt I was stepping beyond the margins of the human world, into some purer, wilder element. And yet, as I sat sifting and cleaning the tiny crustaceans I’d gathered, I struggled to suppress a disturbing thought. It is very likely those organisms contained microscopic