The egg came before the chicken.
Eggs came first ahead of chickens
Experts at Geneva University believe they have finally figured out the answer to the age-old question as they say eggs appeared a long time before the animals first evolved.
Scientists analysed a single-celled species called Chromosphaera perkinskii that was discovered in 2017 in Hawaiian marine sediments and the discovery suggests that the genetic programmes responsible for embryonic development - the process in which a fertilised egg develops into an embryo - were present before the emergence of animal life.
The team explained that nature possessed the genetic tools to "create eggs" before it "invented chickens".
Previous studies suggested that hard-shelled eggs did not emerge until 300 million years ago.
Marine Olivetta, the first author of the study, said: "It's fascinating, a species discovered very recently allows us to go back in time more than a billion years."