Researchers discovered a pair of conjoined whales off the coast of a Mexican Lagoon on Sunday.

However, the twin whales did not survive and researchers are speculating the possible cause of their death. The calves were found in Mexico's Laguna Ojo de Liebre, or Scammon's Lagoon.

"The twins discovered in Scammon's Lagoon did not survive and most likely were miscarried. The carcass is only about seven feet long, versus the normal 12 to 16 feet for newborn gray whales. Alisa Schulman-Janiger, an American Cetacean Society researcher, pointed out that the twins were severely underdeveloped and wondered whether the birth or stillbirth might also have killed the mother," Grind TV reports.

According to Grind TV, the rare occurrence is the first documented case of Siamese twins for gray whales. The calves are believed to be gray whales because the species normally swims to the warm lagoons of Mexico to give birth every year.

"They give birth during the southbound journey, or in the lagoons, and nurse their calves for several weeks before embarking on their northbound journey back to the Bering and Chukchi seas," Grind TV reports.

The journey from the Baja California peninsula to the Mexican lagoons is estimated to be nearly 6,000-mile trip from their home. According to multiple reports, the gray whale calves are usually born between the last week of December and the first two weeks of January.

"Subtropical lagoons along Baja California's Pacific coast are particularly popular with gray whale mothers, which typically give birth to a single calf the winter after they mate, according to the University of San Diego's Birch Aquariumm," The Huffington Post reports.

Grind TV reports the Siamese twin gray whales were taken to study. The Pacific gray whale population is about 21,000. You can check out more images of the calves here.