This machine looks like a tinker-toy wheel, with six spokes and six segments around the circumference.  Each of these sections has a uniform round cross-section -- like a pipe -- and a specular reflection like metal.  The machine also has a shadowy structure - about 1/3 of the wheel's diameter across - connected to the hub on the left side.  The wheel is standing on edge on one of its 6 flat sides but appears to be slightly tipped over (leaning away from the camera).   It is the most obvious machine-like structure I've ever seen on Mars.

Here's another similar structure:  http://mars_central.tripod.com/fha01230.htm