An exhibition of mummies in Mexico could pose a surprising health risk to humans. Find out why archaeologists are sounding the alarm.

There is a group of mummies in Mexico that you might not want to see. Although they are on display in Mexico City and regularly travel across the country, not everyone considers them safe. Unlike the movies, these mummies are not likely to come back to life. The problem here is the unexpected presence of fungi.

Mexico’s National Institute of Anthropology and History is concerned about the appearance of fungi on the traveling exhibit and the way the mummies are handled and displayed to the public. Known as the “Mummies of Guanajuato”, the exhibit made an appearance in the United States in 2009. However, it was a recent exhibit in Mexico City, featuring six mummies in display cases, that prompted the institute to alert the public, especially since they don’t know how airtight these windows are.

“The fact that they are still on display without biohazard protection for the public is even more concerning,” the institute said in a statement, according to The Associated Press. “According to some published photos, at least one of the exposed bodies, inspected by the institute in November 2021, shows signs of overgrowth of fungal colonies.”

Deadly fungal infections caused by mummies aren’t common, but they’re not new either. IFL Science reports that 10 of the 12 scientists present at the opening of the tomb of King Casimir IV in Poland in 1970 died within weeks of the event, possibly due to fungus. And this is not the only example.

Mexican mummies were never intended to be examples of mummification. Experts believe that the 19th or 20th century bodies were unintentionally mummified, possibly due to the mineral-rich environment, a sealed and dry underground burial vault, or some other environmental cause. Some mummies still have preserved hair, skin, and even clothing, but there are no traces of embalming or other common mummification products.

Mummies have been part of Mexican culture since the 1860s. When the families of the deceased could no longer afford the funeral expenses, the bodies were destined for exhumation. Instead of finding dusty bones, workers discovered whole, intact bodies. These were exhibited because of their state of preservation and the possibility of attracting paying visitors. According to National Geographic, the first visitors went underground to see the mummies, and since 1969 they have been on display in Guanajuato’s museum, the Museo de las Momias.

In the early 1900s, the staging and promotion of the mummy exhibit took on a horrific aspect. Some bodies were positioned with their arms crossed over their chests and their jaws open, giving the impression that the mummies were screaming.

The display style of these mummies has long drawn social criticism. “They’re just ordinary people bearing witness to the times they lived in,” Gerald Conlogue, professor emeritus of diagnostic imaging at Quinnipiac University, told National Geographic. “They walked these streets, they went to the old market. They shouldn’t be a fairground attraction.” In February 2022, an initiative was launched to begin identifying mummies.

Now, social concerns are accompanied by health concerns. “All of this should be studied carefully to determine whether these signs pose a risk to cultural heritage,” the institute’s statement states, “as well as to those who handle them and come to see them.”