This story appears in the June 2018 issue of National Geographic magazine.

Like a detective on the case, a Cornell University professor is using a set of handcrafted glass masterpieces to gauge the health of ocean invertebrates. In the late 1800s Leopold Blaschka and his son Rudolf created more than 700 invertebrates in glass, celebrating the ocean’s astonishing diversity at that time. Drew Harvell, who curates the collection, has a huge spreadsheet that lists every piece. For eight years she’s been searching out the actual animals and matching them to the art, to see what may have changed. She’s found most of them, but some are endangered. In her book, A Sea of Glass, she’s written about it. “The quest to find the living matches connects Blaschka history, current ocean change, and art,” she says.