This interesting tidbit of info I just found on a NASA site. This was found and recorded by NASA on Jan 26, 2005 and yet no one has never heard of it till now. 
Source: http://www.ufosightingsdaily.com/2018/03/giant-alien-head-found-on-mars-and.html​

Evidence of life on Mars is being covered up by Nasa, according to a researcher Barry DiGregorio at a Buckingham University.
The agency’s space explorer, the Curiosity rover, has snapped what may be trace fossils created by soft-bodied creatures on the red planet, he says.
​Source: http://www.dailymail.co.uk