Happy to see you

Most people know of the face on Mars, a mountain-type structure in the region known as Cydonia first photographed by the Viking explorers in the 1970's. It appears similar to a human's face in a helmet, but many are suprised to find out there is also a smiley face. This one is a circular crater with two eyes and a curve for the mouth, and it's uncannily similar to the same design as the 70's hippy image, and the one used in the Watchmen comics/movies.

There seems to be more natural formations on Mars resembling humans than on earth. 

It's name is Galle after its discoverer Johann Gottfried Galle, who discovered the 230km wide anomaly in 1999.  

The term for seeing faces in patterns where there were none is pareidolia, and the actual textbook example given for this term on Wikipedia is the original Martian face.

Life on Mars

The Cydonia face caused much excitement amongst ET fans in 1977 when the first image was seen because it sparked talk of intelligent life on Mars. Further speculation, after examining more images, was that there were pyramids on Mars and even ruined cities. Later missions with more precise cameras produced detailed images which were then 3D mapped to show nothing out of the ordinary when viewed from other angles and lighting conditions.

Crater

As with the more famous human face, it only appears to be a smiley when both the viewing angle and the lighting are both in a certain alignment.

Nereidum Montes

The Mandela Effect here is that news of these smiley faces appears to have "jumped into our timeline" and by their nature ought to be far better known.