Mold can look like the stuff of nightmares, especially if it’s a never-before-seen type of black mold eating a cathedral. It’s creepy, but that’s precisely what’s happening to a cathedral in Portugal. The eight-century-old Sé Velha de Coimbra (Old Cathedral of Coimbra) is the only surviving Romanesque cathedral in Portugal and it’s being slowly devoured by a type of black mold that scientists say has never been seen before.

The mold is part of a newly identified family of microcolonial black fungi (MCBF) called Aeminiaceae. Scientists at the University of Coimbra in Portugal scraped samples of the mold off the limestone sculptures in the Santa Maria chapel of the cathedral. After genetic analysis, researchers at the determined that the mold was something they had never seen before. Their findings were published in the journal MycoKeys. While this strain of black mold is a completely new species, the damage mold can do to old stone architecture is well understood. According to the study:

“Microcolonial black fungi are considered one of the main culprits for the phenomenon of stone biodeterioration, being responsible for severe aesthetic, biochemical and biophysical alterations.”

Not to mention the overwhelming sense of dread when you walk into a medieval cathedral and see a statue of a saint covered in black mold. That’ll make you believe in evil as a tangible force pretty quickly.

The paper continues to describe why these types of mold are so hard to deal with:

They exhibit several physiological adaptations allowing their tolerance to various stress factors, including extreme temperatures, high solar and ultraviolet radiation, osmotic changes, and severe drought.

Despite the supernatural or prophetic implications you’d be forgiven for seeing in this mysterious mold, researchers think it’s been part of the cathedral since it was built, transported to Coimbra on the limestone from which the Sé Velha de Coimbra was constructed, between the 12th and 13th century AD. Due to it’s slow-growing nature, it hasn’t begun to present a problem until now.

The limestone was quarried from from Ançã and Portunhos and was used in the construction of many catholic statues in Portugal as well as in the Royal Hospital in Santiago de Compostela in Spain. Now that this new strain of fungus has been identified, it’s entirely possible that it might be growing on these other sculptures as well. As of now, scientists believe hypothesize that the Aeminiaceae is endemic to the Iberian peninsula.

Another way to put it would be this thing is a centuries-old monster, growing larger and larger throughout the ages, relentlessly devouring religious iconography. This is why flamethrowers were invented, right?