Vampires cannot die. Long ago, in pre-history, they infested the earth so totally that they swarmed starving beneath the soil on every available surface and piled in the seas abyssal deep beneath the reach of the suns rays.
Ultimately nature revolted against this grotesque perversion and, somehow, in one blinding flash, they were totally destroyed.
When they were finally wiped out there were so many that the calcite remains formed an entire geological strata. But time has eroded and folded them so now the thin band of pale rock that is the only remnant of the first great age of vampires is only another geological phenomena.
But, still, they cannot die. Very occasionally one was fossilised wholly enough that, millions of years later, freed by erosion and decay, it can wriggle loose from the soft rock.
The fossilised stone skeleton of a precambrian vampire. Cracked and deranged by its entombment. Utterly totally insane.