In the video, a weirdly-shaped grey octopus can be seen leaning against a plant on the ocean floor.
Suddenly, the odd creature morphs into the plant behind it to seemingly disappear without a trace.
The mind-blowing video was originally released as part of a Ted talk in 2008, but resurfaced on Reddit yesterday.
More than 14,000 people have seen it and viewers were understandably stunned.
One wrote: “Isn’t this pretty much exactly what we’d expect ‘alien life’ to look like?
“If they were discovered living under the ice on Europa or something, we’d be terrified – but they’re here, living in the ocean, so they’re food at Japanese restaurants and used to predict football matches.”
Another viewer commented: “This is the most terrifying thing I’ve ever seen.”
A third added: “Would not be shocked to find out that octopuses are straight up aliens.”
And as others were quick to point out, this could mean there are a whole variety of camouflaged species swimming in the depths of the sea.
“So, octopuses can camouflage and disappear from sight?” a fourth asked.
“So, if there is an ancient gigantic octopus-like creature dormant in the bottom of the sea… we might not be able to see it?”