A Great Treasure

There it was. He had found it.
On the podium stood the most enormous egg he had ever seen. Its yellow shell was coated in a sheen of ice, freezing it shut for eternity.
Stefan chiselled at the ice, as a storm rumbled overhead.
He took it home, back to his kingdom, and was rewarded well.
It was named the greatest treasure, placed in the museum. The warm air cocooned it, cracks blossoming.
Those who went near it went mad. Those who touched it died. Thunder rumbled, and the ground shook, as skies darkened.
For within the egg, something stirred.