The scientists behind NASA's $2.5 billion Curiosity rover mission on Mars on Tuesday explained the nature of a tiny gleaming flower embedded in Red Planet rock.

The Planetary Science Institute's R. Aileen Yingst, deputy principal investigator for the MAHLI team, delivered the expert verdict. The "flower" is a relatively large mineral grain or "a pebble, if you wish," measuring about a tenth of an inch (2 millimeters) wide. "It could be a lot of things, but without some chemical information to back me up, I'd really hesitate to say what it is," she said.

She pointed out that a couple of similar, darker-colored grains could be seen embedded nearby. The important thing is what such rounded grains have to say about the scene's history. "They've been knocked around, they've been busted up. They've been rounded by some process," she said. That suggests that running water helped form the rock.

The "Martian flower" made a splash on the Internet, in part because it looked so different from the surrounding rock in a microscopic-scale picture from Curiosity's Mars Hand Lens Imager, or MAHLI. Few people thought it was actually a flower, though it looked a bit like one.