Bristol, United Kingdom, October 7, 2008--A bladder stone the size of a small egg can be seen in this X-ray photo of Polly, a five-year-old African pancake tortoise. The IUCN classifies the tortoise as vulnerable.

Vets at the Bristol Zoo cut a hole in the bottom of Polly's shell to remove the stone, which measured 1.5 inches (3.7 centimeters) by 1.2 inches (3 centimeters). Polly measures 5.5 inches (14 centimeters) from head to tail.