Which is the cuter animal Internet sensation - Lil Bub the kitty or Boo the doggy?
Lil Bub's owner Mike Bridavsky says: "Boo is cuter." Referring to the two animals which have been dubbed the world's cutest dog and cat by the media and netizens, he explains: "You see Boo and it looks like a toy. Lil Bub's cute in a less traditional way. I don't think of her as an Internet celebrity. I think of her more as a hero, an inspiration and a really remarkable animal more so than just a cute animal."
Lil Bub, whose breed cannot be verified, was a rescue kitten with multiple birth defects that had a hard time finding a home. She is afflicted by severe dwarfism, giving her short stubby limbs, and suffers from a rare condition called osteopetrosis, which makes her bones grow harder and denser.
As a result, she does not seem to age and has been called a "perma-kitten".
Mr Bridavsky, who adopted her three years ago, says: "People didn't want to take Lil Bub because it was so strangelooking and so small. They were worried that it would cost a lot of money or be a potential heartbreak.
"When I saw it, I thought, well, besides being so remarkable and unique, I thought that it needed someone to take care of it because no one wanted to. And I absolutely wanted to."
He and a veterinarian did not think that Lil Bub would live very long at first, but she is now three years old and "healthier than ever".
Speaking to Life! from his Indiana home in the United States, he says he has received messages saying Lil Bub's pictures helped a student through graduate school and has been an inspiration for a chronically ill child.
Compared to the eight-year-old Pomeranian Boo, which has amassed 13 million likes on its official Facebook page since 2009 to go with plush toys made in its likeness, Lil Bub has just over 700,000 on Facebook since 2012.
But the underdog, er, undercat is now the star of an Animal Planet show, Lil Bub's Special Special.