The social media giant flagged a photograph of a 16th-century statue of the sea god Neptune in the Italian city of Bologna, Mashable reported. The picture of the sculpture—which was created in the 1560s—was featured on the Facebook page of local writer and art historian Elisa Barbari called “Stories, curiosities and view of Bologna.”

Facebook told Barbari that the picture violated the company’s privacy policies. “It shows an image with content that is explicitly sexual and which excessively shows the body or unnecessarily concentrates on body parts,” the company said in a statement.

The company added: “The usage of images or video of nude bodies or plunging necklines is not allowed, even if the use is for artistic or educational reasons.”

Barbari reacted with shock, telling Mashable, “I wanted to promote my page but it seems that for Facebook the picture of our Giant [Neptune] is a sexually explicit image … This is crazy!”

On her Facebook page, she then posted: “Yes to Neptune, no to censorship.”

https://www.facebook.com/ElisaBarbari/photos/a.388302727872985.76106.117874421582485/1226330140736902/?type=3

Facebook later told Mashable that blocking the photo was a mistake. “Our team processes millions of advertising images each week, and in some instances we incorrectly prohibit ads,” the company said.

This isn’t the first criticism of Facebook blocking an image. In September, the site removed a memorable photo from the Vietnam War of a naked girl fleeing down the road after use of napalm bombs. The photo is one of the most iconic images of the war, and its photographer, Nick Ut, won the Pulitzer Prize. Facebook later reinstated the photo.