An archaeological find in the southern city of Yavne discovered an intact 1,000-year-old chicken egg – one of just a rare few that currently exist in the world, the Israel Antiquities Authority (IAA) reported on Wednesday.

The unbroken egg was excavated as a standard archaeological dig ahead of the construction of a new residential complex in the city and was discovered inside a sewage ditch that dates back roughly 1,000 years to the Islamic period.

Dr. Lee Perry Gal, an expert in fowl in the ancient world, explained that fragments of eggshells have been found at some of the oldest sites in Israel, such as the City of David, Caesarea, and Apollonia, almost no intact eggs have been discovered due to their fragility.

“Even by international standards, this is an extremely rare find,” Gal said.

“Very rarely, we find whole ancient ostrich eggs, which have been preserved due to their thicker shells,” Gal added.

Ella Nagorsky, another archaeologist with the IAA, said that “Even today, eggs barely survive in supermarket cartons. It’s amazing to think that this is a 1,000-year-old discovery. It appears that the unique preservation of the eggs is the result of the conditions that surrounded it for hundreds of years – a soft bottom to the sewage ditch, which apparently included soft human waste that protected [the egg].”

Chickens were farmed in Israel as far back as 2,300 years ago. The Islamic Period, which began in the 7th century CE, experienced a significant drop in the number of swine bones in the area because of the Muslim prohibition against eating pig.

“Families looked for a substitute protein available from small animals that did not require preservation or cooling, and found it in fowl and eggs,” Gal said.

Unfortunately, Gal admitted that a small crack underneath the egg enabled most of its contents to leak out. This development left trace amounts of the white, which is being stored for future DNA analysis.