Louise Bourgeois’s spiders, towering and delicate, are located around the world, from Kansas City to Seoul. The largest sculpture in the series, “Maman” — French for mother — stands 30 feet tall at London’s Tate Modern; powerfully crouched, its spindly bronze legs taper down to exquisite pinpoints. Underneath the spider’s abdomen, a metal egg sac full of white marble orbs hangs ominously over viewers’ heads. Though Bourgeois didn’t begin her spiders until she was in her eighties, they have become her best-known works.