Unlocking the chemical structure of the substance has been so far as tough as the sporopollenin itself, the journal Nature reported. "They call sporopollenin the 'plant diamond' because you can't ...

Subsequent x-rays showed that the stone was riddled with microscopic diamonds, the hardest substance known ... to invoke an extra-solar origin for the diamond," the scientists concluded in ...

The material withstands 58 percent more stress than diamonds, and could have "remarkable mechanical properties".