It was kept inside a large well from Roman times in Buckinghamshire (England). It was a speckled egg, probably a chicken, discovered during excavations in 2010 at Berryfields, a site west of Aylesbury where a new housing estate was to be built.

Around 1,700 years ago, someone kept this specimen along with three other eggs, a woven basket, ceramic vessels, coins, leather shoes and animal bones. Over time, the well became flooded and almost all the zygotes ruptured, “emitting an incredibly sulfurous smell,” recall the researchers from the Oxford Archeology company in charge of studying the place.

“Despite the incredibly fragile nature of the eggs, the team on site was able to recover one intact,” they added in a statement. The most surprising thing is that in recent weeks it has undergone a micro-computed tomography and it has been found that it is still full of fluid, as well as an air bubble.

“The work is never done when archaeologists leave the site. Post-excavation analyzes can take many years,” indicate the specialists, who in 2019 already published a monograph that revealed human activity at this site from the Neolithic to the post-medieval period.

After analysis in the laboratory, the researchers took the egg to the Natural History Museum in London, where it was inspected by expert Douglas Russell, senior curator of the collection of bird eggs and nests. “We were all surprised to hear that the zygote is even rarer than we thought and that with its liquid center intact it is the only known example of its type in the world,” he says.

The goal now is to ensure both future research and long-term storage of the fertilized egg. The liquid inside appears to be a mixture of yolk and albumen (the main protein in the egg white) that could reveal the secrets of the bird that laid it almost two thousand years ago.

Often, specialists say, pieces of shell are found, but not intact eggs, beyond those that have been discovered mummified in Egypt. The Aylesbury specimen was probably placed in the well (located next to a Roman road and used for brewing beer) as a votive offering, while pieces of bread may have been in the basket.