Stickney Crater (Natural Colors; credits: NASA)

The most prominent feature here is the large impact crater Stickney. With a diameter of 9 Km, it is the largest feature on Phobos. A series of grooves and crater chains is obvious on the other parts of the moon.
Although many appear radial to Stickney, previous studies show that the grooves radiate from a different point on Phobos. Hypotheses for their formation vary.
Some scientists believe the grooves and crater chains are related to the formation of Stickney, whereas others think they may have formed from ejecta from impacts on Mars that later collided with Phobos.
The lineated textures on the walls of Stickney and other large craters are landslides formed from materials falling into the crater interiors in the weak Phobos gravity (less than 1/1000th the gravity on Earth).