However, this photo is from Mars as claimed by NASA.
This is an actual object in 3 dimensions out there in the background. Look at the shading around its edges. The shading gets lighter at the edges indicating this is a real object out there with sun light reflecting more on its top than on its bottom.
It can't be a dust particle on camera as object is not spotted in other Mars Curiosity images prior or after above image.
NASA Original Photograph : HERE
Other Related News Articles:
Wood on Mars NASA leaked Picture
NASA Curiosity Photographed Water Trail On Mars
NASA Curiosity Photographed Fossil Finger On Mars
Japan Kofun Era Tomb Like Structure Found On Mars
NASA Mars Curiosity Photographed Violin Knob On Mars
NASA Curiosity Photographed Fossilized Thigh Bone On Mars
NASA Curiosity Photographed Gigantic Creature Fossilized Spine On Mars