Stone Structure in Mars Taken by NASA Rover (mars.jpl.nasa.gov)

Clearly, aliens......

But for real, what it is?

According to the image timestamp, (2006). The image is from Sol 728.

It's so hard to judge the scale of the thing. How far away is it from the rover? Does anyone know the approximate dimensions?

It's clearly a hat. https://twitter.com/arxpoetica/status/966177376077058048