Lou, W0IT, sent a link to this video to his brother Ralph, AA8RK, who passed it along to me. It’s a 10 Mbyte download, but worth the wait:
It shows a microwave antenna chock full of acorns, but this description doesn’t do the video justice. Click on the photo to download it. Really.
What do we learn from this? Acorns make a good microwave shield.