That's from the right navigation camera of the curiosity rover. There is also an image from the left navigation camera taken at the exact same time and it shows nothing. The timestamp for both images is (2014-07-14T02:06:13.000Z).

https://mars.nasa.gov/msl-raw-images/proj/msl/redops/ods/surface/sol/00688/opgs/edr/ncam/NLB_458574869EDR_F0390444NCAM00295M_.JPG