- Egg laid by the elephant bird could be 800 years old and could fetch £50k
- Elephant bird was largest bird that ever lived and was more than 10ft tall
- Eggs became sought-after rarities and curiosities in the late 19th century
- Thought to be just 25 preserved intact elephant bird eggs left in existence
At 200 times the size of a hen's egg, it is big enough to feed the hungriest family - although the age and price may put them off.
Laid by the elephant bird, the rare egg could be 800 years old and is expected to fetch up to £50,000 at auction at Sotheby's in London on Thursday.
The elephant bird, the largest bird that ever lived, was more than 10ft tall and weighed 70st.
Eggstraordinary: The elephant bird egg is expected to fetch up to £50,000 at auction at Sotheby's in London
Egg-tacular: Sir David Attenborough owns one and ranks it among his most treasured possessions
Flightless and native to Madagascar, it was hunted to extinction some 400 years ago.
Due to their colossal size and extreme rarity, the eggs became sought-after rarities and curiosities in the late 19th-century.
There are thought to be just 25 preserved intact elephant bird eggs left in existence, with most in museums.
Fossilised egg fragments can still be found on the ground in some parts of Madagascar.
David Attenborough, the natural history broadcaster, owns an almost complete eggshell that he pieced together from fragments collected by locals when he filmed Zoo Quest to Madagasar in 1961.
Another elephant bird egg was sold in 2013 for £66,675 - more than twice its expected value.
Bulky: The elephant bird, the largest bird that ever lived, was more than 10ft tall and weighed 70st
Expensive: The giant semi-fossilised egg that is almost 100 times larger than a chicken's egg