The Well water of the tiny Canadian town of Gypsumville, Manitoba (population 65) has been poisoned by an extraterrestrial. The invader: A meteorite which struck down almost a quarter-billion years ago, creating the 40-kilometer-wide Lake Martin impact crater. The ancient impact shattered the granitic ground so that extraordinary amounts of fluoride now taint the well water. Slightly higher than recommended amounts of fluoride can cause mottled teeth, while even higher concentrations can lead to neurological problems and softened bones. This is could be the first time a meteor impact has been tied to a modern health threat, say the geologists who made the discovery.