Conjoined whale calves found in Mexico's Laguna Ojo de Liebre, whose photos were widely shared online, may be the first discovery of its kind.

The conjoined gray whales were found dead, and probably were miscarried, Discovery News reports. The carcass is seven feet long, while calves typically measure anywhere between 12 to 16 feet in length.

While conjoined calves have been reported in other whale species, this may be the first recorded case of Siamese gray whale calves. Alisa Schulman-Janiger, an American Cetacean Society researcher, said the twins were severely underdeveloped and their birth or stillbirth may have killed the mother.

Images of the conjoined twins were posted Sunday to the Guerrero Negro Verde Facebook page. A translated description reads, “Unfortunately, the specimen died. [Its] survival was very difficult.”

Scientists found no evidence of the twins’ mother, adding more questions to what happened to the animals. The carcass was collected for further study.

Video images of the whales were shared on YouTube. Commenters speculate on the possible causes of the whale’s condition including a birth defect or an effect of the Fukushima nuclear disaster thousands of miles away in Japan.

Gray whales are among the greatest migrators, traveling in pods for more than 12,000 miles in some cases. During the winter, the pods typically migrate to the warmer waters off the Mexican coast, according to National Geographic.

The number of gray whales spotted migrating south off the California coast in December was doubled compared to the year before, which may mean the animals are changing their migrating patterns.

"You can see how this year blows all those years away," Schulman-Janiger told the Los Angeles Times. "It will actually take some time before we can figure out why, because the migration hasn't peaked yet."

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