NASA's Hubble Space Telescope snapped this shot of Mars on Aug. 26, 2003, when the Red Planet was 34.7 million miles from Earth. The picture was taken just 11 hours before Mars made its closest approach to us in 60,000 years.

Have signs of ancient Martian life been found inside a Red Planet meteorite?

A team of scientists says that microscopic tunnels and carbon-rich spherules that stud the interior of a Martian meteorite known as Yamato 000593 may have been formed by Red Planet organisms long ago, NBC News reported today (Feb. 25).

The new study, which was published in the February issue of the journal Astrobiology, does not claim that Yamato 000593 harbors conclusive evidence of life on Mars. But the rock may indeed contain something truly special, its authors say.

"We cannot exclude the possibility that the carbon-rich regions in both sets of features may be the product of abiotic mechanisms; however, textural and compositional similarities to features in terrestrial samples, which have been interpreted as biogenic, imply the intriguing possibility that the Martian features were formed by biotic activity," they write in the study, which you can read here.

The famous Martian meteorite ALH 84001 contains a "fossil" that was ruled out as life because of its small size; however, it could still be an autocell — a precursor to life. (Image credit: NASA)

The new study comes 18 years after researchers announced that they had found evidence of possible Martian lifeforms in a different meteorite from the Red Planet, known as Allan Hills 84001 (ALH 84001). Much of the scientific community was unswayed, however, saying ALH 84001's "nanofossils" could be abiotic in origin.

The new Astrobiology paper is already meeting with similar scrutiny and skepticism, as its authors undoubtedly knew it would.

"I don't think the science community will find 'textural and compositional similarities' compelling enough to be proof of a biological origin," Chris McKay, of NASA's Ames Research Center in Moffett Field, Calif., told NBC News.

The lead author of the 1996 ALH84001 paper — which was published in the prestigious journal Science — was David McKay, a scientist at NASA's Johnson Space Center (JSC) in Houston. (He and Chris McKay are not related.) David McKay, who died last year, is also a co-author on the new Astrobiology paper.

The research team plans to continue and expand its investigation of the 30-lb (13.5 kilograms) Yamato 000593 meteorite, which scientists say formed about 1.3 billion years ago on Mars and landed in Antarctica a maximum of 10,000 years ago, after being blasted off the Red Planet by an impact event.

"We have to go to the next step of going in there and tearing these carbon molecules apart," Everett Gibson of JSC, who was involved in both the ALH84001 and Yamato 000593 studies, told NBC News.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.