A few years ago, curator Robin Hansen noticed something unusual about a rock at the Natural History Museum in London, England. She thought it looked like a dinosaur egg.
Dinosaur experts at the museum examined the specimen and found that Hansen was right. It was a fossilized dino egg! Its shape and size suggest that it was laid by a titanosaur—an enormous, long-necked dinosaur. The egg was likely buried in a volcanic eruption about 67 million years ago. Over time, mineral-rich water seeped inside, filling it with agate crystal.
The egg had mistakenly been part of the museum’s mineral collection for 140 years. “It is only now that we recognized this specimen has something extra special,” says Hansen.