A strange creature recently washed up on the shore of an Australian lake. It was found and photographed by a fisherman named Robert Tyndall, who came across it while fishing last weekend.

As a Mirror news story described it, "With the body of a legless crocodile and the head of a dolphin, this strange sea creature looks more like something out of medieval myth than a real animal."

The "monster" was photographed on the banks of Lake Macquarie in New South Wales, Australia. The Mirror described it as having "a long, slender body with scales and a tail like a crocodile with no legs, a head shaped like a dolphin's and a mouth full of razor sharp teeth."

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A photo of the seemingly huge mystery monster went viral, with wild speculation ranging from a dinosaur to a Photoshop hoax. The image was widely shared and spawned headlines such as "Photo of 'Freakish Lake Monster' Terrifies the Internet" and "Prehistoric-Looking Sea Creature with Razor Sharp Teeth Washes Up on the Shore of an Australian Lake."

Within a few days experts had identified it as a pike eel, which, though nocturnal, is common in the lake. Furthermore, despite the impressive size depicted in the photo, it was estimated to be about five and a half feet long—a sizeable eel, but somewhat smaller than the maximum length for that species.

So how did a non-monstrous dead eel end up making international news?

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Optical Illusion

Part of the reason that the creature seemed like a monster is that it appears huge in Tyndall's photo. It's what in photography is called forced perspective, which tricks the eye into making objects appear to be much larger or smaller than they really are. The eel was photographed at a low angle close to the ground instead of from above, as it would normally be seen by a standing adult.

This helps create the illusion of enormity in several ways: First, it puts the carcass higher in the photo and therefore closer to the horizon line. Things that we usually see close to the horizon are often large (such as trees, buildings, and mountains). Second, the angle obscures the tail, which seems to slide gently into the water and is hidden by the reflection from the sky, subtly suggesting that it’s longer than it is. An overhead photograph taken from a higher angle would avoid the sky’s reflection and show exactly where the creature’s body ends.

Furthermore there is nothing in the photo near the carcass to provide a sense of scale. If it had been photographed next to a dollar bill or a Coke can, for example, people looking at the image would have a recognizable scale for reference.

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No one is suggesting that Tyndall attempted to deceive anyone with the photograph—after all, it is a large eel and it’s human nature to try to find angles that make it seem bigger, just for fun. Generations of fishermen have found creative angles to hold fish up to a camera that can make a goldfish look like a whale.

Though some smelled a hoax, there’s no reason to suspect any (intentional) photo manipulation or trickery. It’s a real—and not uncommon—animal in the area.

Social Media Monsters

But the misleadingly magnified photo is only part of the reason the image went viral. As it turns out, the photo did not begin as a mystery at all. In an interview with The Newcastle Herald, Tyndall acknowledged, “I knew it was some kind of eel and it’s a big eel, but it definitely looks bigger. I think everyone enjoys using their imagination. Judging by the comments, it was growing by the minute.”

So if the person who photographed it knew what it was all along, how did a picture of an otherwise ordinary pike eel take on an afterlife as a mysterious monster viral sensation?

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The answer lies in the nature of social media, which is very good at sharing content around the world with only a few clicks but often strips that content of its explanatory context. Countless photographs, infographics, and quotes which were originally accurate in the context in which they originally appeared (in a blog, for example, or on social media) have been shared and taken out of context and become unintentionally misleading in the process.

On Monday a New South Wales man named Ethan Tippa shared the photo on Facebook, along with a colorful query: “This is at swansea boat ramp. What the [...] is it?”—a post that was shared nearly 3,000 times.

In another amusing example of viral misinformation, in some news stories Mr. Tippa is identified as a "father" -- the parent of a child—while in others he is referred to as "Father Ethan Tipper," not only misspelling his last name but suggesting that Tippa (whose Facebook post described the photo with a strong four-letter word) is a priest.

Social media makes sharing photos and memes quick and easy, but even if a photo is shared with all the information needed to correctly identify the "mystery," it only takes one person along the chain to strip it out, and in this social media game of "telephone" it's easy to manufacture mysteries.

Though many experts, as well as Tyndall himself, had a pretty good idea of what the "monster" was, it was widely shared (at least at first) as a complete mystery. Contacting local fishery and zoology experts for commentary of course takes time, and as Mark Twain is credited to have written, "A lie travels around the globe while the truth is putting on its shoes."