THE NEW YORK TIMES: A puppy with a tail on his face gained viral fame this week.

“I would die for Narwhal,” a number of Twitter commenters pledged.

The rescue mutt was named for a marine mammal with a single tusk that sticks out of its face. But instead of a tusk, Narwhal the puppy has a miniature tail flopping between his eyes. Scientists don’t agree on how the unusual heart-stealer came to exist.

A Missouri shelter called Mac’s Mission, which specializes in what it calls “janky” dogs, took in the abandoned puppy. Staff were disappointed that Narwhal’s extra tail didn’t wag. But the appendage didn’t seem to bother the otherwise normal, healthy puppy, and a veterinarian said there was no need to remove it. An X-ray showed no bones.

The likeliest explanation for how Narwhal got his face tail is not all that cute, said Margret Casal, a professor at the University of Pennsylvania School of Veterinary Medicine. The tail is probably Narwhal’s parasitic twin.

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