Warmtoast,
Fascinating ! I remember that my Dad, who had been in Nigeria in the early 1900s, brought a whole lot of cowrie shells home as souveniers. They were used as a form of currency there, he said. They were all very small, as I recall - around 1cm long.
...The radiation belt affects radio and radar transmissions, damages or destroys the arming and fusing mechanisms of Intercontinental Ballistic Missile warheads...
Pity the effect is so transient, as otherwise we would seem to have a good defence against nuclear attack ! (but then, I suppose, a way would soon be found to shield these vital parts from the radiation belt).
Danny.