Residents of Minas Gerais in southern Brazil witnessed a sight that could be classified as both incredible and terrifying at the same time – large clusters of spiders seemingly raining on them from the skies.

One of the residents, who filmed the event, said he was travelling to his grandparents’ farm north east of São Paulo when he noticed the black spots in the sky. The Guardian, citing a local newspaper, quoted him as saying he was “stunned and scared.”

According to experts, although it looked like they were falling from the sky, the spiders were actually hanging in a giant web to catch prey. Adalberto dos Santos, an arachnology professor at the Federal University of Minas Gerais said they belonged to the species Parawixia bistriata, a rare “social” spider that can build fine webs which are nearly impossible for the human eye to see.

This gave the illusion that they were floating. This is said to be a recurring phenomenon in hot and humid weather.

But there is nothing to worry about, because the venom of these spiders is harmless and, in fact, the web helps to keep flies and mosquitoes in check.