Brian's latest find was found by commercial fisherman Christopher Johnson (one of Brian's readers) back in 2008 off the coast of Western Australia. Johnson cut the two-headed baby shark out of a pregnant blue shark that he and his fellow fishermen pulled out of the sea. They're required to cut open pregnant sharks because fetal sharks count against the quota of sharks that they are allowed to have on board.
It's not clear what caused this biological abnormality, but it's likely to have been a result of some mixed-up genetic baking. The most famous pair of cojoined human twins, Chang and Eng Bunker, toured with P.T. Barnum's circus back in the 1800s and coined the term "Siamese Twins" (the Chang brothers were born in Thailand, which used to be known as Siam).
Here are a couple more shots of the two-headed baby blue shark, all by Christopher Johnson.
If you'd like to read more about sharks, check out these articles here on MNN:
All photos reprinted with permission.