How Did I Become the Coffin-Lighter Facing the Mystery?

Suddenly there were some strange things in the sky. Many flights crashed due to this! Radar cannot scan its shape! Thermal weapons cannot destroy it! It is visible to the naked eye, and its shape can be clearly seen, but it is impossible to determine what it is. For a time, these strange things suspended in the sky became one of the great mysteries of our time. Until one day, a skinny old man crawled out of the concrete pavement.