In the first part of our journey through the strange and unexpected sights on Mars, we explored some of the planet’s most baffling features. But the surprises don’t end there. From peculiar rock formations that resemble familiar objects to unexplained anomalies captured by rovers, Mars continues to challenge our understanding. In this second part, we delve deeper into more mind-bending discoveries that seem out of place on the Red Planet.
A “giant’s fingerprint”
Long ago, an object struck the surface of Mars, leaving behind this massive, ridged depression that resembles a fingerprint. Of course, no giant finger was involved. Situated within the larger Airy-0 crater, this formation is the result of an ancient meteor impact. The bright streaks that form the “lines” of the fingerprint are a familiar feature on Mars. Called transverse aeolian ridges, they emerge when sand dunes become covered with a thin layer of dust. This dust likely contains reflective minerals, giving the depression its luminous appearance in the image.
An “angel” and a heart
During the Martian summer, intriguing shapes emerge as the ice recedes. The planet’s south pole is typically covered by a vast ice cap, but when warmer temperatures cause it to melt, patterns in the ancient, reddish sediment beneath become visible. This image, captured by ESA’s Mars Express spacecraft, reveals an angel-like formation alongside a heart-shaped one. These recognizable shapes were formed by meteor impacts that stripped away Mars’ dusty surface layer, exposing the darker sediment below.
A weirdly green rock with “drill holes”
Could a mischievous Martian with a power drill be to blame? That’s an unlikely theory, but it might cross your mind when looking at this peculiar green rock, riddled with holes, which NASA’s Perseverance rover discovered early in its mission. Measuring about 6 inches (15 cm), the rock appears out of place in its surroundings, and scientists are still unsure of its origin. It could be a fragment of a meteor that struck Mars or perhaps a piece of Martian bedrock ejected during an impact event. The cause of most of the holes remains a mystery—except for a small trail of tiny, uniform marks just right of center, left behind by Perseverance’s laser as it analyzed the rock’s composition.
A small “foreign object”
In 2018, a small, rectangular object spotted in Mars’ Gale Crater momentarily alarmed NASA scientists. Resembling a dusty sheet of metal, it raised concerns that it might be a fragment of the Curiosity rover that had mysteriously detached. Fortunately, a quick analysis revealed that the so-called “foreign object” was nothing more than a natural rock flake that had broken off from a larger formation—completely native to Gale Crater.
A strange, white tower
In a striking image taken by NASA’s Perseverance rover in 2023, a towering white column rises against the dark, rocky Martian landscape. This impressive formation is actually a Martian dust devil—an enormous one at that. According to NASA, the swirling vortex surpasses the height of an average tornado on Earth and is five times taller than the Empire State Building. Dust devils form when rising warm air meets descending cool air, and they are incredibly common on Mars—one 2018 study estimated that as many as 145 million occur each day.
A “scar” longer than the Grand Canyon
Resembling a fresh wound in this 2024 image from ESA’s Mars Express orbiter, the Martian feature known as Aganippe Fossa is a striking sight. This deep, shadowy ravine extends roughly 375 miles (600 km), making it even longer than the Grand Canyon, which spans about 277 miles (446 km). Situated near the base of an extinct volcano, the canyon likely formed due to ancient volcanic activity—possibly when a massive pool of magma surged upward beneath the volcano, violently ripping the ground apart, according to ESA.
“Rock candy,” or ultra-rare crystals?
These unusually colored crystals on Mars were found completely by chance. In May 2024, NASA’s Curiosity rover accidentally crushed a small rock in its path, revealing a hidden trove of rare minerals—some of which had never been seen on the Red Planet before. Among them were yellowish crystals composed of pure elemental sulfur. While scientists had long suspected sulfur existed on Mars, they lacked concrete evidence until Curiosity’s unexpected discovery through its unintentional rock-smashing.
A “bullet” hole
What appears to be a bullet hole in the Martian surface could actually be something far more intriguing—a potential shelter for future astronauts. Captured by NASA’s Mars Reconnaissance Orbiter in 2022, this small pit, a few meters wide, sits on the flank of the massive Arsia Mons volcano. Positioned along a lava flow, the hole seems to be a vertical shaft that might lead to an extensive cavern system beneath the volcano. While its depth remains uncertain, it could one day serve as a safe haven for astronauts, offering protection from the harsh radiation that bombards the Red Planet.
An underground “dog”
Unusual formations on Mars aren’t limited to its surface—they exist underground too. In September 2024, scientists analyzed data from multiple Mars-orbiting spacecraft to generate a global map of gravitational anomalies—regions where gravity is stronger than usual, indicating the presence of large, dense underground structures. While most of these dense formations are irregular in shape, one stood out: a peculiar, dog-shaped structure with dark features resembling a tail and ears near the Martian north pole. The origin of this dense, canine-like formation remains uncertain, but it may be linked to an ancient meteor impact or an accumulation of volcanic material.
Debris from outer space?
In 2022, NASA discovered what appeared to be the remains of an “alien” spacecraft on Mars. However, the so-called “aliens” were actually humans—the debris, captured by NASA’s Ingenuity Mars helicopter, was part of the helicopter’s own parachute and backshell. This saucer-like cover had helped slow the robotic craft’s descent as it landed on the Red Planet alongside the larger Perseverance rover. Photographed by Ingenuity from 26 feet (8 meters) above the Martian surface, the wreckage of this human-made technology stood out as strikingly alien against the barren landscape of rocks and dust.
An alien “egg”?
From specific viewpoints, this cratered rock resembles a slimy, green egg from a mysterious alien creature. However, a swift examination by NASA’s Curiosity rover confirmed that the unusual boulder, named Egg Rock, is actually a piece of a meteorite that fell onto Mars at an unknown point in history. Investigating Martian meteorites like this can provide important insights into the planet’s past, though it is unlikely to uncover any extraterrestrial creature habitats.
Debris from Earth?
In 2022, NASA discovered what appeared to be the remains of an “alien” spacecraft on Mars. However, the so-called aliens were actually humans—the debris captured by the Ingenuity Mars helicopter was part of its own parachute and backshell, a saucer-shaped cover that helped slow the robotic craft’s descent as it landed on the Red Planet alongside the Perseverance rover. This fragment of human-made wreckage, photographed by Ingenuity while flying 26 feet (8 meters) above the Martian surface, stands out as particularly alien against the barren landscape of rocks and dust.
Swirling patterns
The unusual patterns etched into the surface of Mars’ Nili Fossae region aren’t alien-made sand art or the Martian equivalent of Peru’s Nazca Lines. Instead, they are mineral deposits rich in olivine, a mineral typically found deep beneath Mars’ surface. How such a large amount of olivine-rich rock ended up on the surface remains an intriguing puzzle for scientists. One possibility is that a massive asteroid impact unearthed the mineral from the Martian interior, scattering it in swirling patterns. Alternatively, a colossal volcanic eruption may have exposed the buried olivine. Its exact origin, however, remains uncertain.
A rock with an, er … crack
Resist the urge to chuckle at this rock captured by NASA’s Perseverance rover in 2021. When its close-up image was first shared with the public, the fractured boulder quickly became the subject of numerous jokes. However, there’s not much out of the ordinary here—Mars is scattered with cracked rocks, though few are as rounded as this one. Perseverance came across this boulder in the dusty Jezero Crater on its 102nd day on the Red Planet.
An alien monolith?
While examining images from NASA’s Mars Reconnaissance Orbiter, amateur stargazers noticed something unusual in the satellite’s data—a strikingly rectangular object resembling the alien monolith from the opening scene of 2001: A Space Odyssey. According to mission scientists, the feature is indeed monolithic in both shape and size. However, it is most likely just a large, naturally occurring rectangular rock.
A crawling robot
Seen from miles above by NASA’s Mars Reconnaissance Orbiter, a metallic robot gleams on the Martian surface below. In this rare instance, the mysterious object is exactly what it appears to be—NASA’s Curiosity rover, steadily climbing Mount Sharp years into its mission to explore the Red Planet. While definitive proof of past life on Mars remains elusive, one thing is certain: it is the only known planet in the universe solely inhabited by robots.
