They are rocks. Popular Science used to be a legitimate periodical, I used to read it when I was a kid. I guess they are a shell of their former self.

@AnneWimsey Mushrooms on Mars: Do These Images Show Proof of Life on Mars?
www.popularmechanics.com
Scientists claim NASA photos show mushrooms growing on Mars.
In their paper, the scientists analyze a variety of images taken by NASA’s Opportunity and Curiosity rovers, as well as the Mars Reconnaissance Orbiter’s HiRISE camera.
Mushrooms could be great for multiple purposes for Mars settlers.
Could there be mushrooms on Mars? In a new paper, an international team of scientists from countries including the U.S., France, and China have gathered and compared photographic evidence they claim shows fungus-like objects growing on the Red Planet.

Later studies refuted the hematite claim. Soon, some scientists coined the term “Martian mushrooms” to describe the mysterious objects, because of how they resemble lichens and mushrooms, while in another study, fungi and lichen experts classified the spheres as “puffballs”—a white, spherical fungus belonging to the phylum Basidiomycota found on Earth.

“Many of these ground-level spherical specimens also have stalks or have shed portions of their outer membranes—possibly crustose—and are surrounded by white chunks and fluffy spore-like material that may consist of leprose.”
Crustose and leprose are kinds of fungus surface textures, where crust or scales form and can flake away.

The presence of these peripheral parts is important, the scientists say, because it helps them make the case that what we’re seeing really is fungus instead of simply some spherical rocks. Mushrooms grow and reproduce like gangbusters—it’s one of the defining characteristics of the entire family of fungi. Small mushrooms grow in about a day, while large mushrooms take up to 4 days.The scientists acknowledge the “evidence” they present isn’t ironclad, and seem to predict the scrutiny that will inevitably come with their paper, writing that “similarities in morphology are not proof of life.”

“It is possible that all the specimens presented here are abiotic. We cannot completely rule out minerals, weathering, and unknown geological forces that are unique to Mars and unknown and alien to Earth. However, growth, movement, alterations in location and shape, constitute behavior, and coupled with life-like morphology, strongly support the hypothesis there is life on Mars.”

This Is How We'll Live on the Moon
But if there really were mushrooms on Mars, what would that mean in a future where humans hope to settle on the Red Planet? Well, the scientists say many fungi on Earth are also extremophiles—meaning organisms that can thrive in conditions considered “extreme” in terms of the usual building blocks of life. So to find mushrooms on Mars is perhaps less surprising than we think.

@barjoe could it be mushroom spores from earlier landings?

@AnneWimsey if they survive, the says Mars can support life. I'm not sure they're just a mineral.