Mysterious stands of 'angel hair' falling through the sky in Portugal have been caught on camera.
And many residents are questioning whether it's been created by a passing UFO.
One local, who did not want to be named, told the Metro: "It fell during the afternoon. I tried to inquire if aeroplanes flew over before, but no straight answer. It happened two weekends in a row.
"Me and a couple of friends sent it to be analysed – and the weirdest things happened. It reacts to UV light. It comes alive."
According to Wikipedia, angel hair is a sticky, fibrous substance reported in connection with UFO sightings, or manifestations of the Virgin Mary. It has been described as being like a cobweb or a jelly.
It is named for its similarity to fine hair, or spider webs, and in some cases the substance has been found to be the web threads of migrating spiders.
Reports of angel hair say that it disintegrates or evaporates within a short time of forming. Angel hair is an important aspect of the UFO religion Raëlism, and one theory among ufologists is that it is created from "ionised air sleeting off an electromagnetic field" that surrounds a UFO.
More scientific explanations suggest that it's an atmospheric natural phenomenon, or caused by spiders.
Some types of spiders are known to migrate through the air, sometimes in large numbers, on cobweb gliders. Many cases of angel hair were nothing other than these spider threads and, in one occasion, small spiders have been found on the material.
Linyphiidae spiders frequently cause showers of gossamer threads in England and the Northern hemisphere.Australia and New Zealand have frequent cases, caused by several native species of spiders and by some introduced species of Linyphiidae.
Also, atmospheric electricity may cause floating dust particles to become polarised, and attraction between these polarised dust particles may cause them to join together, to form long filaments.
What do you think the angel hair is? Leave a comment below.