Now, scientists think that’s because SARS-CoV-2 is actually a genetic hybrid, Ars Technica reports: it seems to be the result of two separate viruses that swapped genes somewhere along the way.

The surface of SARS-CoV-2 is dotted with spike proteins that help it stick onto human cells, like biological Velcro.

While the rest of its genetic code matches a bat virus, the portion of SAR-CoV-2’s genome that creates those spike proteins does not.