Phobos monolith

[2][3] A monolith is a geological feature consisting of a single massive piece of rock.

The monolith is a bright object near Stickney crater, described as a "building sized" boulder, which casts a prominent shadow.

[4][5] It was discovered by Efrain Palermo, who did extensive surveys of Martian probe imagery, and later confirmed by Lan Fleming, an imaging sub-contractor at NASA Johnson Space Center.

[4] The PRIME mission would be composed of an orbiter and lander, and each would carry four instruments designed to study various aspects of Phobos' geology.

[11] The Phobos monolith features in Alastair Reynolds' 2012 science-fiction novel Blue Remembered Earth, wherein its surface has been entirely carved by visiting astronauts into the semblance of a wrecked spaceship.

The Phobos monolith (right of center, casting long shadow) as taken by the Mars Global Surveyor ( MOC Image 55103, 1998).
The location of the monolith ( HiRISE image PIA10368)
The Sun, the planets, their moons, and several trans-Neptunian objects The Sun Mercury Venus The Moon Earth Mars Phobos and Deimos Ceres The main asteroid belt Jupiter Moons of Jupiter Rings of Jupiter Saturn Moons of Saturn Rings of Saturn Uranus Moons of Uranus Rings of Uranus Neptune Moons of Neptune Rings of Neptune Pluto Moons of Pluto Haumea Moons of Haumea Makemake S/2015 (136472) 1 The Kuiper Belt Eris Dysnomia The Scattered Disc The Hills Cloud The Oort Cloud