“Even if we get just one or two hatchlings, I will be very happy,” said Gerald Kuchling, a project leader for the Turtle Survival Alliance, a nonprofit conservation organization. “Even a single one would give hope for the recovery of this magnificent animal. It would be a turn.”

Quite a turn, actually. The Yangtze giant softshell turtle — thought to be the largest freshwater turtle in the world — was once common in the Yangtze and Red Rivers. But by the late 1990s, pollution, hunting, dams and development had driven it to the brink of extinction.

There are only four known specimens remaining, and only one female — an 85-year-old resident of the Suzhou Zoo. For years, biologists have been trying to coax her and her 100-year-old mate to produce hatchlings. So far the pair have disappointed scientists, with the female laying clutch after clutch of unfertilized eggs.