Researchers have been left "amazed" by a rare discovery inside a "unique" bird's egg preserved for more than 1,700 years—finding that it still contains liquid.
The egg was originally found during excavations that took place between 2007 and 2016 at a site known as Berryfields in Buckinghamshire, southeast England.
During the excavations, archaeologists uncovered a large, waterlogged pit or well dating between A.D. 270 and A.D. 300 during Britain's Roman period.
Inside the pit, archaeologists found pottery vessels, coins, leather shoes, animal bones and a woven basket with a cache of eggs inside it.
"Of particular interest were the eggs, which were a rare and exciting find. Despite the incredibly fragile nature of the eggs, the team on site were able to retrieve one intact," a blog post from Buckinghamshire Council's Heritage and Archaeology Team reads.
"In Britain, this was a unique find," Edward Biddulph, senior project manager with Oxford Archaeology (OA), a charity that was involved in the Berryfields excavations, told Newsweek.
In order to learn more about the egg, which was likely laid by a chicken, OA's conservator Dana Goodburn-Brown took it to Chris Dunmore, a paleoanthropologist at the University of Kent, England, in August 2023.
Dunmore and Goodburn-Brown had the egg micro-CT scanned at the university and found that it was full of liquid and contained an air bubble.
"This is presumed to be the remains of the yolk and white, and certainly when two other eggs found with the intact egg broke up after their exposure to the air, they released a liquid that gave off a sulfurous smell, suggesting that the eggs held the original contents," Biddulph said.
In September, 2023, OA took the egg to the Natural History Museum (NHM) in London and discussed the find with Douglas Russell, senior curator of birds' eggs and nests, and his colleague, Arianna Bernucci.
The pair were "very excited at seeing the egg, never having seen anything quite like it before," Biddulph said.
"We were all amazed to hear that the egg is even rarer than we had realized, and with its intact liquid center is the only known example of its type in the world," Buckinghamshire Council's Heritage and Archaeology Team's blog post read.
Roman-period eggs are known in Britain, but only survive as shell fragments—making the Berryfields egg a "very rare" find, according to Biddulph.
"In other parts of the Roman world, like Italy, Roman-period eggs have occasionally been found intact, but very little research has been carried out on their contents, if any," he said. "Douglas at the NHM considered it to be the oldest unintentionally preserved bird's egg in the world. There are mummified eggs that are older, but the Berryfields egg is uniquely special, as we would not normally expect anything so old to survive intact."
The age of the pit in which the egg was found suggests that it as at least 1,700 years old, according to Biddulph.
"The pit had originally been used pit to extract water for malting and brewing. The eggs survived, because they had been buried in a layer of soft wet silt or mud, which had not only prevented the eggs from being crushed in the ground, but created anaerobic conditions, thus inhibiting the action of bacteria that might have cause the contents of the eggs to decay," he said. "Other organic objects, which normally would have decayed, were found with the eggs, including [the] basket.
"After the inhabitants of the Roman roadside settlement at Berryfields had stopped using the pit to extract water for malting and brewing, they used the pit for ritual purposes, placing coins, ceramic jars, and of course eggs into the pit as food and other offerings to the gods or for luck—just as we still throw coins into fountains. The basket, which probably contained bread, was also placed into the pit for this purpose."
It is possible that the eggs and bread were deposited as part of a funerary ceremony, for example, according to Biddulph.
Given the uniqueness of the find, the egg has "tremendous" research potential, Biddulph added.
"Usually, archaeozoologists and other archaeologists researching ancient birds only have the bird bones and, far less commonly, fragments of eggshell to use for analysis. Having the egg's contents available for research will open up a far wider range of research opportunities," he said.
One issue researchers hope to unravel is to confirm which species laid the egg. This could help reveal information about the bird and the environment in which it lived. But from an archaeological perspective, the egg is significant because it could yield data about the use of birds and chickens (if confirmed) in the Roman world.
"Currently we know relatively little," Biddulph said.
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Correction 02/13/2024, 1:44 PM ET: This article was updated to say the Natural History Museum (NHM), not the National History Museum.
