A chicken in China is being hailed as a miracle after it laid a monster egg containing two yolks and another egg inside it.

Locals were amazed to find the egg, which was three times the size of a normal egg, weighed in at over 200 grams.

According to the UK's Guardian, the 87-year-old woman who owned the chicken thought it was dying as it tried to lay the egg.

She said she had not seen anything like it before, but the chicken had been laying the oversize eggs for the past three weeks.

This was thought to be the fourth or fifth one it had produced.

The chicken had reportedly shunned the corn the rest of the hens were eating, so was being fed a different rice diet.

It's unknown whether this has caused the over-development of the eggs.

While an egg within an egg is fairly common in the chocolate variety, it's nearly unheard of to have a fully-formed egg inside another one.

- © Fairfax NZ News