“The night we conceived the Crochet Coral Reef project in 2005,” the artists Margaret Wertheim and Christine Wertheim have said, “we joked that if the Great Barrier Reef in our home country, Australia, ever died out, our handcrafted reef may be something to remember it by.” Coral is one of the most beautiful of all nature’s phenomenons, and one of the most important. A marine invertebrate that forms reefs in tropical oceans, it is the foundation for ecosystems that support countless species. It is also the ocean equivalent of the “canary in the coal mine.” Pollution and rising water temperatures kill coral, turning it white and leaving ghostly graveyards. In 2005, the Wertheims and a global community of crocheters began creating “a woolly taxonomy that simulates the hyperbolic frills of corals, kelps, and other sea creatures.” It’s an homage to these fantastical underwater forms, whose survival is interlocked with our own. “Crochet Coral Reef” is the first exhibition in this season’s MIT Museum series “Oceans.” —Laura Jacobs