Doctors are bewildered as to how an extraordinarily shaped blood clot came out of a patient.

On Monday, the New England Journal of Medicine tweeted a startling picture as part of its “Images in Clinical Medicine” photo series, which features photos of medical anomalies.

The rare blood clot, which is a cast of the right bronchial tree. Gavitt Woodard/The New England Journal of Medicine ©2018 The rare blood clot, which is a cast of the right bronchial tree.

The photo, upon first glance, is eerily engaging, resembling a red tree that may have sprouted from the imagination of Tim Burton. But it’s not anything fantastically fictional — it’s a real blood clot that came out of the body of human being and is the exact shape of a lung passage.

More specifically it’s a six-inch-wide, unbroken cast of the right bronchial tree, part of the tubular network that distributes air to the lungs.

An unnamed 36-year-old male patient who had been admitted to ICU for aggressive end-stage heart failure spontaneously coughed up the medical marvel, according to Georg Wieselthaler, a transplant and pulmonary surgeon at the University of California at San Francisco who spoke to The Atlantic. It occurred after the patient had been coughing up much smaller clots for days. When this particular clot came out of the patient, it was initially “oddly shaped” and “folded in on itself,” per the Atlantic. When Wieselthaler and his team delicately spread out the clot, they discovered “that the architecture of the airways had been retained so perfectly that they were able to identify it as the right bronchial tree based solely on the number of branches and their alignment.”

They were stunned that it came out completely unbroken.

When the image hit Twitter, users were transfixed by it.

No. Freaking. Way.

— Paul Smith (@SmithRamparts) December 4, 2018

U r telling me the pt expectorated this piece of bronchial tree??! Thats next to impossible! Awesome

— Ferrah Shaamile (@farahdawood2) December 3, 2018

I'm going to think about it every time I have a cough.

— Natalie_Page (@Natalie_Page) December 4, 2018

That is one CRAZY story. I was sure that had been an autopsy finding

— Mdub (@mwsun) December 3, 2018

Yeah but the coughing though. I mean I can't even imagine. I mean it had to be agonizing in the first place actually dislodging this thing from its mooring. Then additionally your airway is at least partially occluded, plus the gagging. I mean it must be terrifying and agonizing.

— Matt DeBoard (@matt_deboard) December 6, 2018

Unfortunately, the patient who coughed up the curious clot died from complications of heart failure a week later, the Journal said.

Though the clot is extremely unusual, it’s not completely unheard of.

In 2005, a pregnant 25-year-old woman coughed up a similar blood clot that was a copy of the bronchial tree, per the European Journal of Cardio-Thoracic Surgery.

Thankfully this patient, and her unborn child, survived.