On an ordinary street, a shiny metallic-looking object could just be a coin or a bit of trash. On Mars, when NASA’s rover Curiosity spots something gleaming, it’s grounds for talk of aliens and cyborgs.

Eagle-eyed watchers noticed something curious in a picture taken by one of Curiosity’s cameras on Jan. 30. An Italian image editor named Elisabetta Bonora pointed out to the Universe Today that in the midst of the rocky landscape, there’s a tiny protuberance that looks shiny.

“It looks fairly smooth, and in fact it is not covered by dust as is the case for metal surfaces that tend to clean easily,” Universe Today writer Nancy Atkinson wrote.

Bonora speculated that the object could be made of a tougher material that’s more resistant to erosion than the rock around it. Huffington Post writer Michael Rundle commented that it looked like "a robotic arm."

If it was a robotic arm, it would have to be from a very tiny robot -- the protuberance is at most half a centimeter high, Atkinson said.

NASA representatives haven’t yet commented on the object, but earlier sightings of strange objects have typically been revealed as rock formations or parts of the rover itself.

Earlier in January, Curiosity spotted another anomalous bright object that some viewers dubbed a “Martian flower.”

Later, NASA scientists decided the flower was likely just a large grain of mineral that happened to stick out – an especially shiny fragment about a tenth of an inch wide. Other, more darkly colored pebbles have been found near the shinier “flower.”

“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,” researcher R. Aileen Yingst told NBC News in January.

The roundedness of the grains suggests that they were formed through some force, possibly running water.

In October, Curiosity spotted another small bright object that turned out to be a bit of plastic shaken off from the rover itself. At the time, a New Orleans publicist named Domatron Graves created a spoof website and fake press release showing that Curiosity had found what suspiciously looked like Mardi Gras beads. The prank earned Graves a call from someone at NASA’s Jet Propulsion Laboratory, asking him to take down the official space agency logos from his materials.

Meanwhile, NASA has a bigger picture to look at. On Saturday, Curiosity drilled into the Martian bedrock for the first time, creating a hole about two-thirds of an inch wide and about 2.5 inches deep in the fine-grained sediment. It’s the first time any robot has drilled into a rock on Mars.

"The most advanced planetary robot ever designed is now a fully operating analytical laboratory on Mars," NASA Administrator John Grunsfeld said in a statement. "This is the biggest milestone accomplishment for the Curiosity team since the sky-crane landing last August, another proud day for America.”

Over the next few days, Curiosity will draw the sample inside itself for further processing.

Scientists are hoping that the knowledge they gain from such samples could further our understanding of Martian geology, including any possible ancient seas that once flowed on the Red Planet. The rover is also searching for signs that Mars could have once harbored life.

Curiosity is the largest rover sent to Mars thus far and is equipped with a suite of scientific gadgets: three cameras, four spectrometers, two radiation detecters, an environmental monitoring station and an atmospheric sensor.