A pet owner was left reeling after noticing one of his beloved family cat's legs had fallen off. It was only on closer inspection that the bizarre truth revealed itself to him.

Cat content makes up a sizable portion of all that is good on the internet. In fact, feline videos have been shown to provide us with a boost in energy and positive emotions while also decreasing any negative ones.

In a 2015 study published in the journal Computers in Human Behavior, almost 7,000 people were asked to complete a survey describing how cat videos affect their moods. The results showed that the vast majority of those taking part in the study felt less anxious, sad and annoyed after watching cat content.

This can be a force for good, but you have to wonder how some would have been left feeling about the photo that Mark, a dad living in Phoenix, Arizona, shared of the family cat Lucky. The pet is a reasonably new addition to the household, at less than 1 year old, with Mark openly admitting he is "not a cat person."

"I even have a cat allergy," Mark told Newsweek. "After years of telling my kids 'no cats,' I finally caved in and my 13-year-old daughter now has Lucky."

The feline has already made quite the impression and even has his own Instagram account @lucky_the_cat_and_his_two_dogs and a few fans to boot.

Owner Mark might well rank among them now. His stance on Lucky certainly appears to have changed in the wake of what happened—or didn't happen—a couple of days ago.

"I was standing in the kitchen getting dinner ready, and Lucky had been playing with a dog toy," Mark said. "At some point, I turned my head and saw Lucky lying on the floor with his leg tucked under himself, and the dog toy right in front of his leg."

That might sound innocent enough but, to Mark casually glancing over, it looked like something else entirely. "I did a hard double-take because, at a glance, it looked like his leg fell off," he said. "After looking closer and realizing what was really going on, I took a photo to share with my wife and kids. We all had a good laugh."

Eager to caption the optical illusion for posterity, Mark took a picture of Lucky appearing one limb short and shared it to Reddit under the handle u/HabanyGaming.

"I am not on social media and initially had no intent of sharing the photo any further, but every time I looked at it, I got a good laugh," Mark said. "After a couple days, I decided to post the photo on Reddit because I thought others might have a chuckle as well."

Laugh they most certainly did with the post racking up almost 30,000 upvotes.

Most saw exactly what Mark saw on first glance. "Seriously I had to take a second look," one viewer posted, with another writing: "That's one way to make your heart skip a beat."

A third commented, "That's amazing and also horrifying," with a fourth adding: "You must be amazingly calm, he would have run away from me when I screamed at the top of my lungs. Walking in on this would have set me off …"

Mark is surprised at how big the post got. "I had no idea the photo would go viral, with over 1 million views in the first couple days. I had tons of people commenting and asking all sorts of questions about Lucky," he said.

Even better still, Mark's daughter is unaware of Lucky's new celebrity status. "I didn't even tell my 13-year-old that I posted Lucky's photo online," Mark said. "I ought to tell her after school."

It is a pretty big turnaround for someone who insists they aren't a "cat person."