NASA’s Curiosity rover has sent back a pair of very curious photos since March that have resurfaced in conspiracy circles as evidence of a “genuine spaceship” and “thigh bones” visible on Mars.

Alien hunters and UFO enthusiasts are celebrating after two photos appear to show distinct signs of life on Mars. The first photo causing jaws to drop in the reddit conspiracy theorist group Martian Archaeology shows what appears to be fossilized bones or petrified wood protruding from the red planet’s surface. The photo dates back to 2014 and NASA responded to the online uproar then by acknowledging -- but dismissing -- that the "alien thigh bone" could be linked to extraterrestrial life. The debris pile from the Curiosity’s photograph already has convinced some wishful-thinking alien enthusiasts of extraterrestrial activity on Mars.

Photo: NASA

"After years of research and study, I'm convinced now, more than ever, that there is much more to Mars than what NASA admits to," a reddit user named TJ Devereaux remarked. “I'm certain life, including water, and intelligent life forms, once occupied the planet, and ... big leap here ... that both still exist, in much smaller quantities."

Read: NASA's Mars Rover Looks Like It Came From The Future To Explore An Alien Planet

Images of the same bone-like object taken 10 days apart show it had grown larger, causing many to speculate it could be a fungus formed on the supposed "alien bone."

The second image from NASA’s robotic Opportunity rover, also known as MER-B or MER-1, appears to show a shiny, metallic object on Mars’ surface that provoked speculation that it is an alien spacecraft. But several commenters in reddit’s “UFO” forum point out that, like most NASA images from the Curiosity and Opportunity, it’s difficult to gauge the actual size or details from the grainy photo.

Photo: NASA

Curiosity Rover's Findings After Five Years On Mars:

NASA’s Curiosity rover landed in Mars’ Gale Crater on Aug. 5, 2012, using a complex and never-before-attempted maneuver involving a giant parachute, a jet-controlled descent vehicle and a bungee-like apparatus labeled a “sky crane.” NASA says Curiosity's mission is “to determine whether the Red Planet ever was, or is, habitable to microbial life.” The rover, which is about the size of a Mini Cooper, is equipped with 17 cameras and a robotic arm that features several specialized laboratory-like tools and instruments to analyze objects on Mars’ surface.

The Curiosity mission has produced more than 4,700 usable images from Mars’ surface, including 26 new images posted Wednesday. An ancient Martian lake and other indications of Earth-like microbes are among the findings revealed by the rover.

But not everyone is convinced the photos show definitive signs of life on Mars.

“The object certainly appears to be artificial. We know that the rover was taking pictures of its own entry debris at that time. There's nothing particularly alien about the object in question — it could easily be entry debris,” Reddit user “Once Returned” suggested.

Others noted that regardless of the shiny object’s significance, it could be labeled an “Unidentified Landed Object.”

Read: Curiosity Rover Left 5 Years Ago, Here Are The Top Mars Images

“One explanation is that the object is a piece of debris from the Mars rover itself or from its sky crane landing system,” Nigel Watson, author of "The UFO Investigations Manual," told the Daily Mail. “Unless we get more detailed information this is another case of wishful thinking.”