In 2000 the Mars Global Surveyor captured many images of the Medusae Fossae Formation when a NASA image specialist discovered a very unusual object half buried in the Martian soil what appeared to be a crashed alien craft which is approximately 190 meters wide and impacted the surface at a low angle.
Despite frantic efforts to make this amazing finding public the image mysteriously disappeared several times from the website of the NASA specialist, but surprisingly the image released on October 16, 2000 remained on the NASA servers.
But after rechecking the original image it has now been deleted as well, which is of course very suspicious.
Left the original Mars image - Right image shows Page Not Found - Image has been removed.
http://www.msss.com/moc_gallery/m07_m12/images/M11/M1101534.html
Luckily, in 2016 UFOvni2012 saved the original image showing the crashed UFO which you can see in the video below.