Strange black objects (NOTE: Subscribers can still listen to this show) have been seen from 200 miles above the surface of Mars. They appear when the surface of Mars begins to warm up, and show up in the same location most of the time--then during the Martian winter, they disappear. They have been described as looking like "little black flecks dotting the ridges, mostly on the sunny side, like sunbathing spiders sitting in rows."
They were first spotted in 1998. They were once thought to be microorganisms (NOTE: Subscribers can still listen to this show too), but the latest theory is that they are geysers of carbon dioxide.
On Yahoo News, Eric Pfieffer quotes researcher Phil Christensen as saying, ""If you were there, you'd be standing on a slab of carbon dioxide ice. All around you, roaring jets of carbon dioxide gas are throwing sand and dust a couple hundred feet into the air. The ground below would be rumbling. You'd feel it in your space boots."