Fir tree grew in man's lungs.

Dang, I guess it's true what they say about swallowing apple seeds... From Ananova:

Astonished surgeons have removed a two-inch long fir tree growing inside a patient's lungs.

Doctors thought Artyom Sidorkin, 28, had cancer when he began coughing up blood and complaining of agonising chest pains.

But as they operated to remove a tumour the medics were amazed to discover the perfectly formed spruce thriving inside the lung.

"I blinked three times and thought I was seeing things," said surgeon Vladimir Kamashev at Izhevsk Hospital in Russia.

Doctors believe that Artyom breathed in a tiny seed which then began growing in his lung and that the sharp pains were the plant's needle-like leaves digging into his lung.