Hand Sculpture With Thumb Found On Mars, NASA Source, April 7, 2017, UFO Sighting News.

Date of discovery: April 7, 2017
Location of discovery: Mars
Source NASA photo: http://www.midnightplanets.com/web/MSL/image/01450/1450MR0071820610703222E01_DXXX.html

This is an official NASA site that uploads the most current rover photos to it. Unlike places like Gigipan index, which is not an official site and therefore carries less authority to it.

I found a giant hand, and it has clear wrinkles and even a thumb. It also has a bone like object sticking out from the wrist area (I didn't highlight it). There was a small face and what looks like a second large hand to the far left. 

It is often said that the defining trait which separates man from the animals is an opposable thumb. While many may take that remark in jest, there is in fact much truth in it. Without the opposable thumb, human beings might never have attained the highly civilized, sophisticated, and technological lifestyles that many of them enjoy today.

Opposable thumbs are required for efficient gripping of objects as well as performing fine manipulations upon them. As soon as man’s tools evolved from crude blocks of stone into more refined objects, the skill of refining objects with his hands on a tiny scale became indispensable to him. After all, virtually all of the early accomplishments of human civilization were built through sheer manual labor! 
Scott C. Waring
 Above is the hand, below is a face. 
 Below is two hands and one face.