If you don’t like spiders, don’t watch this video, because it is truly terrifying for arachnophobes. A man in Brazil filmed thousands of spiders seemingly skittering across the sky. They’re actually suspended on very fine webs strung between the power lines, but what they are and where they came from are still a bit of a mystery.

After watching the video, filmed by 20-year-old Erick Reis in the city of Santo Antonio da Platina, biologists chimed in on their opinions about the spider horde, some saying the creatures were the social colonial species Anelosimus eximius, which lives in communal webs and share certain duties like rearing young.

Now experts say that this species is more likely a semi-solitary kind of spider which gathers with other spiders when it’s time to mate then goes off to spin its own individual web. Many arachnologists suggest that the species is Parawixia bistriata, an orb-weaving spider. However, no orb webs were caught on film, so the spiders are still a bit of a mystery.

And now, prepare to freak out: