A YouTube video, which went viral on social media this week, has once again sparked alien conspiracy theories. The video shows artefacts discovered in a cave in Mexico. They appear to have alien-like figures on them.

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The video went viral on January 25, with some people speculating that it could be proof of aliens having made their way to Earth thousands of years ago. The video was shared on YouTube by UFOmania and has received more than 182,000 views until the time of publishing this article.

The video claims that Mexican artefacts depicting alien life have surfaced and are popular among locals. One of the eerie photos shows the artefacts with long faces and wide eyes, while another object apparently shows spaceships flying through the air.

"Many will know the Klaus Dona Artefacts. There are Tons more where they came from. More and more locals and farmers are showing their private Artefacts [sic]," the YouTube video description reads. "Fortunately they did not give their Artefacts to the Smithsonian Institute and the like for further Analysis."

The video divided social media users, with some claiming that it is the best evidence of extraterrestrial life. However, several others, who were not convinced, raised questions over the authenticity of the object.

Believers of the alien conspiracy theory suggest that the objects were made by aliens themselves.

"awesome artifacts ! so glad the Smithsonian didn't get their hands on them - we never would have seen them," one YouTube user commented.

"Incredible Evidenciary support of the fact that extraterrestrials have been engaging the human race for a very long time!" another said.

"Best evidence yet !!! I mean they did believe in half human half animal creatures," a third user said.

Here's what the naysayers claimed:

"If they are confident that their relics of aliens why did they not get examined by the Smithsonian," one user commented on the video.

"Assuming these are genuine artefacts, these are probably not depicting aliens," another user wrote.

"Depicting humans with exaggerated features is something people have been doing for a long time. It's called caricature."

The authenticity of the video has not been verified and there is no concrete evidence to back the "alien" claims.

Meanwhile, these artefacts are not the only things that are believed to have been constructed by aliens. The Nazca Lines in southern Peru are mysterious straight lines that are believed to be as many as two millennia old.

There are around 300 geometric shapes, 70 figures of animals and it can be visible from above. Due to its mysterious nature, the lines are often said to be one of the biggest examples of an alien work on Earth.