No, you’re not seeing double!

A rare two-headed baby turtle was found at a protected nesting site on Cape Cod in Massachusetts last month — and is miraculously surviving against the odds.

The tiny diamondback terrapin hatchling, which weighs as much as a nickel, has bicephaly, a rare developmental anomaly, the Cape Wildlife Center shared on Facebook.

The pint-sized turtle was brought to the wildlife center by the Mass Audubon Wellfleet Bay Wildlife Sanctuary be closley monitored and cared for.

Bicephaly — where an animal is born with two functioning heads on one single body — is typically caused by the incomplete splitting of a single embryo during the formation of identical twins, according to Live Science.

The team at Cape Wildlife Center said they have only seen two other bicephalic cases in the last five years — making the double-headed baby turtle “especially rare.”

“While we’ve encountered this unusual condition before, every case gives us another opportunity to learn more about these fascinating animals’ anatomy and physiology,” the center wrote.

“For now, our team is monitoring this little one’s (two’s?) appetite, growth, and behavior closely.”

The discovery of the two-headed turtle is an uncommon example of bicephaly in turtles, according to Zak Mertz, CEO of New England Wildlife Centers, which encompasses the Cape Wildlife Center. 

“It is fascinating and an area that certainly merits more study,” Mertz told the outlet. “We are excited to care for these two and learn as much as we can to inform future study in the process.”

Based on available research, Mertz said the rare, double-headed condition “is caused by both genetic and epigenetic factors.”

“It may have to do with the relatively long lifespan of the turtles, their preference for returning to the same nesting sites, and a limited gene pool due to their conservation status,” he said

But bicephaly could also “be influenced by environmental factors such as the temperature, humidity during incubation, physical characteristics of the nesting sites, or potentially even things the parents are exposed to in the environment,” Mertz added.

While having two heads is rare, it’s not unprecedented — with other recent examples of animals with bicephaly including a two-headed porpoise found off the coast of the Netherlands and a double-headed dolphin found on a beach in Turkey.

Double-headed and partially duplicated sea turtles typically have significant craniofacial — the structure, bones, and soft tissues of the skull and face — and spinal abnormalities, according to a 2021 study titled, “Two heads are not always better than one.”

Turtles with two-heads typically are smaller than their hatchling counterparts and face survival challenges because of their abnormal anatomy, the study found. 

Because having two heads directly threatens a turtle’s survival, researchers say monitoring these rare cases offers a vital window into the health of the entire species and its habitat.

Diamondback terrapins are found in brackish marshlands along the Atlantic and Gulf coasts of the US and are classified as threatened by the Massachusetts Endangered Species Act, according to the outlet.