The egg was laid by hen Matilda kept in a hutch at the bottom of a garden
A hen in Suffolk has laid an 9cm (3.5in) high egg - four times the size of a normal egg, its owner said.
The egg, laid by hen Matilda, is about four times larger that the average chicken's egg, said owner Mark Cornish, 36, of Ipswich, Suffolk.
Mr Cornish said the egg has a circumference of 21cm (8.3in).
He said he was shocked when he pulled the enormous egg out of the hutch in his garden. "I thought a goose must have got in there by mistake," he said.
"It does not look as though a chicken would have laid it. I think it is four times bigger than a normal egg.
"The problem is the shell is paper thin. It's already had a crack in it.
"Matilda has not been laying eggs that long - this is only her fourth or fifth - so it must have come as a bit of a shock for her."
The lecturer and his partner, Denise Bartram, have kept their four hens, Matilda, Phyllis, Ada and Polly, in their garden for the past six months.
Despite her huge effort, Matilda, the Dutch Welsummer, did not make the top of the world record charts.
A spokesman for Guinness World Records said: "The largest hen egg was a five-yolked egg measuring 31cm (12.2in) around the long axis, 22.8cm (9in) around the short and weighing nearly 340g (12oz).
"It was laid by a Black Minorca at Mr Stafford's Damsteads Farm, Mellor, Lancashire, in 1896."