A man undergoing treatment for heart failure coughed up a massive blood clot in the perfect shape of his lung passage, and the image has drawn equal amounts of amazement and disgust online.

The image, published in a photo essay of medical anomalies from the New England Journal of Medicine, shows the bright-red, 15-centimetre-wide clot with branches identical to the right bronchial tree of the patient’s lung.

According to the image’s description, the 36-year-old male patient spit up the clot “during an extreme bout of coughing.” This provided the patient with temporary relief, but he died nine days later due to heart failure complications.

“We were astonished,” Georg M. Wieselthaler, the pulmonary surgeon who operated on the patient, told The Atlantic. “It’s a curiosity you can’t imagine—I mean, this is very, very, very rare.”

Wieselthaler had the patient’s heart connected to a device designed to help blood flow, but these devices can cause clotting, which could explain the size of the clot. He added surgeons still aren’t sure how it could have come out without breaking.

While extremely uncommon, this isn’t completely unheard of. In 2005, the European Journal of Cardio-Thoracic Surgery published a similar photo of a bronchial tree-shaped clot that a pregnant 25-year-old woman coughed up. This clot was much smaller, however.

The image has gone viral since it was posted last week, with people comparing it to a lit-up Christmas tree, a pile of licorice and coral. Others are asking for advice on how to avoid seeing the image.

Don’t understand why you’re all so horrified by that blood clot. It looks like the kind of coral people decorate their vacation houses with... pic.twitter.com/aK0SD5md51 — Jamie Kenney (@LaComtesseJamie) December 7, 2018

Saw these trees at halftime and thought of that giant blood clot. That story has ruined me. pic.twitter.com/hz7yAxfOwl — Jenny Vrentas (@JennyVrentas) December 7, 2018

Oh God what if that blood clot ends up hosting the Oscars — Eric Haywood (@EricHaywood) December 7, 2018

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“I come for the depressing news updates!”

“I come for the hate speech!”

“I come to have a picture of a horrifying blood clot tweeted into my time line at random intervals!” — Dave Itzkoff (@ditzkoff) December 7, 2018

A pretty decoration or a bronchial blood clot in lights. You decide. #Icantunseeit pic.twitter.com/43tHPE6ooi — Snarky mama (@SarcasticBride) December 8, 2018

I coughed up this blood clot pic.twitter.com/UtSKQZSmrh — Quinn Sutherland (@ReelQuinn) December 7, 2018