After an in-depth analysis of the genetic material from hundreds of swabs taken from the walls, floors, machines and drains inside the Huanan Seafood Wholesale Market in Wuhan, China — a site that’s been described as an epicenter of early spread of Covid-19 — scientists say they now know exactly which species of animals were in the same area where investigators also found the most positive samples the virus that causes Covid-19.

Genetic evidence from a new report suggests the coronavirus pandemic most likely spilled over from animals in the Wuhan market.

“It’s one of the most important data sets on the early pandemic and on the origin of SARS-CoV-2,” says Florence Débarre, an evolutionary biologist at the the French national research agency CNRS, and co-author of the Cell analysis.