Have we found any evidence of rocks or other matter on Earth that could only have come from Mars?

What is the latest evidence of life on Mars/evidence that there hasn't been life on Mars

What sorts of chemical signatures could a Mars rover detect that would indicate life was once present on Mars?

If evidence, either structural or biological, is found will the public be made aware of its discovery, and if so, how long would you supress the information before making it public?

Did people have evidence that they believed proved that there were little green men or similar aliens on mars?

Is it likely that Curiosity might photograph mini- or microfossils might found at the Shaler outcrop.