Curators at a British museum have discovered what they claim is the youngest mummy from ancient Egypt — a mummified fetus believed to be between 16 and 18 weeks old.

For more than 2,500 years, the tiny body has been resting in a small wooden coffin, the arms crossed over its chest. The coffin was excavated at Giza in 1907 by the British School of Archaeology and came into the collection of the Fitzwilliam Museum in Cambridge, U.K., the same year.

“It is a perfect miniature example of a wooden coffin of the ancient Egyptian Late Period, dating from 664-525 BC. The lid and box are both made from cedar wood,” the museum said in a statement.

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“Although the coffin is deteriorated, it is clear that the wood was carefully carved on a painstakingly small scale and decorated,” it added.

Until now it was believed the coffin, which is a little more than 17 inches long, contained the mummified remains of internal organs that were routinely removed during the embalming of bodies. Indeed, only a wrapped package could be seen inside.

Such package was “carefully bound in bandages, over which molten black resin had been poured before the coffin was closed,” the museum said.

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But when curators asked the Cambridge University’s Department of Zoology to CT scan the coffin for a forthcoming exhibition, they were presented with pictures of the remains of a tiny human body.

Although the skull and pelvis had collapsed, five digits on both hands and feet and the long bones of the legs and arms were all clearly visible.

“From the micro CT scan it is noticeable that the fetus has its arms crossed over its chest. This, coupled with the intricacy of the tiny coffin and its decoration, are clear indications of the importance and time given to this burial in Egyptian society,” the museum said.

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Experts estimate the fetus, whose gender is unknown, died as the result of a miscarriage at no more than 18 weeks gestation.

“This discovery is the only academically verified specimen to exist at only sixteen to eighteen weeks of gestation,” the museum said.

Indeed, two mummified fetuses, placed in individual coffins, were found in King Tutankhamun’s tomb, but they were more developed at about 25 weeks and 37 weeks into gestation. DNA analysis in 2010 revealed the fetuses can be Tutankhamun’s daughters.

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The new finding shows “how an unborn child might be viewed in ancient Egyptian society,” Julie Dawson, head of conservation at the Fitzwilliam Museum said.

“The care taken in the preparation of this burial clearly demonstrates the value placed on life even in the first weeks of its inception,” Dawson said.

The miniature coffin is currently on display as part of the exhibition Death on the Nile: Uncovering the Afterlife of ancient Egypt until 22nd May 2016 at the Fitzwilliam Museum Cambridge.