In 1908 an earth grazing object, air bolide, created an explosion over the Kungusta river in Russia. The remoteness of the event prevented an investigation for over a decade which itself was cursory. One hundred years later the best explanation is that the explosion, though immense, was too small to be a comet or rocky asteroid which would have been completely destroyed. More likely an iron asteroid created a plasma fireball before before leaving the atmosphere and returning to space explaining the scarcity of meteor debris.
