Somewhere over the modern day United Kingdom, around the 5th century or so, a thunderstorm grows...
Huge bolts of lighting arc through the clouds, and a massive anvil head forms above. The storm rages for only several minutes, and when the thunder reaches its crescendo... the anvil explodes in a gigantic blast of wind and magenta light!!
For mile- I mean Kilometers around, birds fly into the air, and the trees and grasses sway.... The shockwave echoes through the land.

The locals are terrified, and believe it a bad omen...

They have no idea.

From the former center of the storm, a fist sized metallic marble falls from the sky, glowing slightly from the heat of its appearance.
It plops into a lake, with a burst of steam, and settles to the bottom, where it soon releases small clouds of... dust?
No. It's something much finer than that........