Scientists working in Mexico's Laguna Ojo de Liebre made a startling discovery on Sunday: a pair of conjoined gray whales floating in the surf.

Researchers believe that the conjoined twins probably did not survive birth and were likely miscarried by their mother. The whales are noticeably underdeveloped, measuring only seven feet as opposed to 12 to 16 feet, which is the normal size for newborn gray whales. Although the mother has yet to be located, the twins have been collected for further study.

There have been documented cases of conjoined twins in other species such as minke whales, but this may be the first such documented case among gray whales.

See footage of the twins here: