A man has been discovered to have two extra penises by medical students dissecting his body, marking only the second time ever someone has been found to have three penises.

This incredibly rare triple penis phenomenon was found by students at the University of Birmingham Medical School in the U.K. during a dissection of a 78-year-old man who had donated his body to science, according to a new paper in the publication Journal of Medical Case Reports.

According to the researchers, the man may never have known he had three penises.

This condition, known as triphallia, was only seen in a human for the very first time in 2020 in a newborn, and is thought to affect one in every 5 to 6 million live births.

“Triphallia, a rare congenital anomaly describing the presence of three distinct penile shafts, has been reported only once in the literature,” the researchers wrote in the new paper. “Without dissection, this anatomical variation would have remained undiscovered, suggesting the prevalence of polyphallia may be greater than expected.”

Having two penises, known as diphallia, has been seen in around 100 human cases, and occurs once in every 5.5 million live births. Usually, doctors remove the extra penises at birth if they are externally visible, but they are often left alone or go unnoticed entirely if hidden inside the body.

The 78-year-old man appeared to have normal genitals externally, but once his penis was dissected, the students discovered two other tiny duplicate penises hidden inside his scrotum.