At first I thought the bottom of the moon was disintegrating.
Before 2007 the teller put aliens in the same category as Bigfoot: fun to think about, but if they were real there would be hard evidence by now. He's a veteran, and in 2007 he was living in the Midwest and out jogging at 3:30 in the morning.
He stopped to catch his breath and looked up at a large full moon, about halfway up the sky. As he watched, the lower right edge of the moon seemed to start disappearing. It took him a moment to understand that something was moving in front of it.
It was a triangle, a perfect equilateral triangle with straight sides and sharp points, solid black, with no lights and no sound at all. It slid slowly across the face of the moon until it covered almost all of it, leaving only three thin slivers of moonlight showing along its sides.
Then, instead of passing on, it stopped. For about two and a half minutes it turned slowly on its centre point in front of the moon, rotating and shifting position as if it were, in his words, dancing there. Then it rotated back to the left, the way it had come, and slid off the moon's edge.
Once it left the moon he couldn't see it at all. He hadn't seen it approach and couldn't see it go. Against the dark sky, without lights, it was simply invisible. He only saw it at all because it happened to pass in front of the brightest thing in the sky.
The sharp corners struck him most. He had always assumed an aircraft would need rounded edges, and this looked like something deliberately designed. At first he thought it might be enormous and very high up. Later, given how crisp its edges were, he decided it was more likely around a hundred feet across and flying low, perhaps under a thousand feet.
He told very few people. Years later he read accounts from other witnesses of silent black triangles, many describing the same slow, deliberate movement. It changed his mind. He no longer puts these things in the same category as Bigfoot.