A patient suffering from heart failure reportedly coughed up a huge blood clot that somehow retained the shape of the lung passages it had blocked. The Atlantic's Haley Weiss reports that "Doctors Aren't Sure How This Even Came Out of a Patient"

In Wieselthaler's case, blood eventually broke out of his patient's pulmonary network into the lower right lung, heading directly for the bronchial tree. After days of coughing up much smaller clots, Wieselthaler's patient bore down on a longer, deeper cough and, relieved, spit out a large, oddly shaped clot, folded in on itself. Once Wieselthaler and his team carefully unfurled the bundle and laid it out, they found 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.

He died a few days later. I looked it up. Sorry.