This is a sticky thread that's commonly seen during and after UFO sightings. In some instances they can be identified as spider webs (since some spiders travel through the air), but there are many instances where the substance can't be identified. Reports of angel hair reach as far back as ancient times..
In 1961 carpenters hard at work in the Louisiana city of Shreveport were assaulted by a rain of green peaches. The strange fruit were the size of golf balls. Any reasonable weather-based explanations were ruled out by near-by weather authorities.
Someone in Ohio must have pissed off a wizard. That's the only way to explain how stones smashed down on Harrisonville in October 1931. This was hardly the only instance of stone rain, but in this case the only culprit—crazy trouble makers—was ruled out when everyone in town was rounded-up and the stones kept coming.
Even Stranger Meat
In what has lovingly been dubbed the “Kentucky meat shower,” square two-inch pieces of meat fell near Rankin, Kentucky. One doctor identified the meat as possibly being lung tissue from a human or a horse, but other pieces were identified as muscle. Locals latched onto the idea that it may have been vomited up by buzzards.
In mid February '16 strange cloud-like objects settled on the ground Doukkala, Morocco. The most likely explanation would seem to be sea foam, but conspiracy theories abound, including weather manipulation, UFO exhaust, and strange insidious weapons.