Just when we thought we had scanned, surveyed and scrutinized every inch of our nearest neighbor, along comes a fresh Martian mystery.

And it’s a real whoduggit.

During a pass over Mars’ south pole, NASA's Mars Reconnaissance Orbiter snapped an image of what appears to be a deep, dark hole.

Just a shred of light, thanks to it being summer on the planet’s south pole, illuminates a shimmery patch of ice in the depths.

As NASA notes, the picture was taken with the powerful High Resolution Imaging Science Experiment (HiRISE) camera from the spacecraft’s perch 125 to 200 miles above the planet's surface. The HiRSE can zoom in on objects that are about three feet in size.

High Resolution Imaging Science Experiment, or HiRISE HiRISE, pictured here, uses a telescopic lens to reveal the surface of Mars in unprecedented detail. (Photo: NASA/JPL)

The hole itself, based on the image scale of around 20 inches per pixel, could be several miles wide. And how deep? Well, that’s a mystery we can all dig into.

As for how it came to be, NASA is of two minds: a geographical feature, like a lava tube, may have collapsed. Or something hit the surface really, really hard, jabbing deep into the rock.

Now, before our minds turn to extraterrestrial excavators, it’s important to keep in mind that holes can also be, well, holes.

Mars, befitting a planet that’s been kicked around by celestial objects for millennia, bears many a dent. NASA aptly calls the surface a "Swiss cheese terrain." Then there are the volcanoes that have carved funnels into ice fields. Not to mention the massive floods that once raged there, gouging out deep pits in its surface.

The geography of a planet, as we know from Earth history, can be formed by all kinds of natural skullduggery that doesn’t necessarily point to sentient sculptors. Still, among the various craters and depressions, the hole in Mars' south pole is particularly intriguing.

For one, it’s massive and it’s deeper than other craters that have been obviously caused by blunt force trauma. But mostly, it’s what we can’t see that titillates. The hole suggests that we’re literally scratching the surface of what Mars can tell us.

We’ve enjoyed scratching our alien itch on Mars for years. Earth has been sending planetary paparazzi to Mars for decades now. And those probes reliably deliver scenes that initially cause a stir only to fizzle into buzz-killing ... geography.

Remember the Martian skull, a rock that resembled our own cranial containers so closely it was promptly trumpeted as a dusty fossil from an extraterrestrial civilization?

A rock shaped like a skull photographed on the surface of Mars. Many Earthlings were disappointed when NASA smashed the alien skull theory on the rock of reality. (Photo: NASA/JPL)

Or the rock that looked just like a tree stump?

A rock that looks like a tree on the surface of Mars This tree-like rock sparked fantasies of ancient Martian forests until ... NASA. (Photo: NASA/JPL)

It’s a funny thing about rocks. They can be a lot like clouds in that we often see what we want to see in them.

In 2012, we saw something in those rocks that may have been the closest thing to a statement from Mars itself to Earthbound gawkers. The Martian rover Curiosity captured an image of a rock offering, perhaps, the most crassly creative gesture yet. It appeared to be giving us the finger.

Mars rock that looks like a finger This image got people buzzing about a Martian finger, just laying there among the rocks. (Photo: NASA/JPL)