Emily pulled the 9 STONE specimen out of the ground at Cotswold Water Park in Gloucestershire with the help of her father Jon, 40.
She took the fossil - which she affectionately dubbed 'Spike' - to school to show her friends who, she says, all thought he was 'great'! The fossilised sea creature has a spiral-patterned shell with inch-long bristles jutting from it to ward off predators
The Rieneckia odysseus fossil, which is almost 16in in diameter, is the remains of a mollusc that lived in the oceans during the Jurassic period. Amonites became extinct 65 million years ago.
Her dad Jon said the fossil was an 'amazing find'.
Emily was reunited with her find at the Gateway Information Centre near Cirencester where he is displayed, after being painstakingly cleaned by geologist Neville Hollingsworth.
It will be shown under its official title of 'Rieneckia odysseus' - although to proud Emily, he will apparently always be 'Spike'!
Emily, from Chippenham, Wiltshire, said: 'It is so exciting to see him. I was very happy when I first saw him and now he looks very shiny.'
Her father added: 'It is breathtaking how much work has gone into restoring Spike. After it has been displayed here we will bring it back home but it will be tricky to store because we have small children and it is very spiky.'
Emily, now six, made the discovery in March last year during her first archaeological dig.
Dr Hollingworth, who spent a year restoring the fossil, said: 'This is the first ammonite of this kind to be discovered whole in Britain. The rest have all been fragments.'
Have you or your kids ever dug up anything amazing?
Old coins? Time capsules?
Or have you buried stuff for future generations to find?