Who will shell out for this pre-17th century fossilised bird egg?

A sub-fossilised egg belonging to an extinct Elephant Bird has been put up for auction today.

Click here to see more photos of the unusual egg, and a fragment from a dodo's femur bone

At 30cm tall and 21cm in diameter, the impressive egg is about 100 times larger than an average chicken egg, and larger than eggs laid by dinosaurs.

The Elephant Bird itself - a native of Madagascar - stood at around three metres, and is thought to have gone extinct between the 13th to 17th centuries.

James Hyslop, a Scientific Specialist at Christie's, said: "It's very rare to find one that's complete. To see one in such perfect condition is a real treat."

The unusual egg is expected to fetch around £30,000 when it features in Christie's "Travel, Science and Natural History" in April. It will be sold alongside other unusual exhibits such as a fragment from a dodo's femur bone.