An adorable puppy has gone viral online for having what looks like a second tail growing from its forehead. Workers at a pet shelter in Missouri who rescued the dog named him Narwhal—after the marine mammal whose single long tusk resembles a unicorn’s horn.

The pup’s unique appendage has intrigued researchers worldwide. Although it looks like a tail, it likely isn’t one, says David Kilroy, a veterinarian in Ireland. Instead, he says, the dog’s skin may have formed in an unusual way while he developed inside his mother’s womb. Despite his “horn,” Narwhal seems to be thriving. “I don’t think he’ll have any problems,” says Kilroy.