This tiny hippo was a big surprise. Her mom, Bibi, gave birth at the Cincinnati Zoo—six weeks early! The baby, Fiona, weighed just 29 pounds. Nile hippos like her should be three times bigger than that at birth. Little Fiona could not stand or nurse from Bibi.

Do you know how to feed and care for a premature baby hippo? Zoo workers didn’t either! They had never done it before. They had to scramble to answer questions: “What do we feed her?” “Should we put her in the water?” “How do we make her stronger?” “How would a hippo mom take care of a premature baby in the wild?”

You can read about those questions—and how zoo workers answered them—in a new book called Saving Fiona. The director of the Cincinnati Zoo, Thane Maynard, wrote the book. Mr. Maynard says Fiona has taught zoo workers a lot.