Mars just got weirder: Curiosity rover spots coral-shaped rock formed by ancient water

It looks like coral from Earth’s oceans but it’s sitting on Mars. On 24 July, NASA’s Curiosity rover captured an image of a tiny, oddly shaped rock inside Gale Crater. The one-inch-wide object, though clearly a rock, has delicate, branching structures that make it resemble coral typically found in marine reefs back home.

NASA released the image on 4 August, taken using the rover’s Remote Micro Imager, a telescopic, high-resolution camera mounted on Curiosity’s robotic arm. The object isn’t alive, of course. But it’s telling us something critical.

“Curiosity has found many rocks like this one, which were formed by ancient water combined with billions of years of sandblasting by the wind,” NASA said in its official statement.

Not the first strange find

This isn’t the first time Curiosity has come across formations like this. Similar flower-shaped and reef-like objects have been spotted before in Gale Crater, suggesting Mars has a long and complicated water history.

The newly discovered rock, along with another called “Paposo”, measuring about two inches across and also found in July—is thought to have formed when Mars was a much wetter world. The process is surprisingly familiar: water carrying dissolved minerals moved through tiny cracks in rock, eventually drying out and leaving hardened mineral veins behind. Over time, strong Martian winds eroded the surrounding rock but left those veins exposed, resulting in the coral-like shapes we see today.

“This common process, seen extensively on Earth, has produced fantastic shapes on Mars, including a flower-shaped rock,” NASA added.

Evidence of a watery past

While the planet today is dry and cold, findings like these strengthen the belief that Mars once had liquid water—and a lot of it. Ancient rivers, lakes, and possibly even oceans may have existed, changing the landscape in ways scientists are still working to understand.

“Water carried dissolved minerals into rock cracks and later dried, leaving the hardened minerals behind,” NASA explained.

The agency also pointed to recent images of geological structures nicknamed “spiderwebs,” captured in June, as further evidence. These intricate ridges echo patterns found in the new coral-like rock and hint at long-term underground water activity.

A slow, steady climb up Mount Sharp

Curiosity has been exploring Mars since it landed in Gale Crater in 2012. The crater itself is a massive impact basin, about 154 kilometres wide, located between the planet’s southern highlands and northern plains.

The rover’s main goal is to study rock layers, look for signs of habitability, and track Mars’ environmental history. It’s made progress, slowly and methodically, covering over 35 kilometres in 13 years. That pace is intentional—Curiosity stops frequently to drill, analyse soil, and transmit data back to Earth.

Today, it’s navigating the lower slopes of Mount Sharp, a five-kilometre-tall mountain rising from the crater floor. In this region, the rover is currently studying boxwork formations—a network of ridges believed to be the result of underground water shaping rock over time.

“Remarkably, the boxwork patterns show that even in the midst of this drying, water was still present underground, creating changes seen today,” NASA said.

New tricks for an ageing Rover

Thirteen years in, Curiosity is still working but not without challenges. Its wheels are worn. Its mechanical systems have aged. And its power supply driven by the decay of plutonium in a multi-mission radioisotope thermoelectric generator is slowly fading.

To keep the mission going, engineers have adapted. Through software updates, they’ve taught the rover to multitask, saving energy and time.

“We were more like cautious parents earlier in the mission,” said Reidar Larsen, a flight systems engineer at NASA’s Jet Propulsion Laboratory. “It's as if our teenage rover is maturing, and we're trusting it to take on more responsibility.”

One of the key upgrades? Curiosity can now finish its daily tasks and shut itself down early to conserve power. That might mean just 10 or 20 minutes saved per day, but over time it adds up.

“Together, these measures are doing their job to keep Curiosity as busy as ever,” NASA said.

Curiosity has revealed more about Mars than anyone expected in 2012. It has uncovered carbon chains dating back 3.7 billion years, found strong evidence of a past carbon cycle, and mapped areas where microbial life might once have existed.

The discovery of the coral-like rock may not prove life ever existed on Mars, but it adds to the growing pile of geological clues pointing to a once-habitable environment.

And as long as the rover keeps moving, more secrets will likely follow.

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