David discovers the curiosities that have led to accusations of forgery but have ultimately helped us rethink evolution. When early explorers brought the first specimen of a duck-billed platypus back to England in 1799, it was thought so bizarre it was deemed a hoax, while the midwife toad became the centre of a raging scientific storm in the 1920s that led to accusations of fakery.

Sir David Attenborough looks at some amazing quirks of evolution; he encounters two examples where nature has tinkered with the aging process.

The single spiral tusk of the narwhal inspiration for tales of unicorns and the myriad variations on the twist of the snail shell have delighted and fascinated naturalists and artists since the dawn of civilization.

A look at two curiosities of nature - an animal with a super-stretched neck and another with a stretchy tongue.

David looks at two examples of animal patterns that have baffled scientists for years.