Even more development art for my Stonehides Chapter Space Marines!
It's common practice for Space Marine Chapters to employ some manner of test or challenge to determine whether or not an Aspirant (one who desires to be a Space Marine) is worthy of joining the ranks of Battle Brothers. The exact nature of the test can vary widely between chapters, but virtually all of them involve extremely high degrees of physical, mental and in some cases spiritual challenge. The Stonehides make use of an Exposure Trial, which requires the aspirant to travel alone and on foot to the Chapter's fortress-monastery
[link] from a set distance many, many kilometers away. Only those with the highest degree of physical fortitude, and knowledge of how to ply the harsh desert for water and shelter, can survive the trek.
The inhabitants of Arghor, the Stonehides' homeworld, are primarily grouped in nomadic tribes. Thanks to superstitions instilled following the Chapter's founding, the inhabitants of Arghor know their resident Space Marines only as "the Stone Warriors, who live in the Great Rock." The Stonehides' Ceremonial Armour (worn specifically for interacting with the Arghorans) reinforces the Stonehides' status as "Men of Stone." To create the Ceremonial Armour, the Chapter artificers grind native Arghoran stones into a fine powder, and mix it with a ceramite-based paste, which is then brushed onto the armor. The Ceremonial Armour's eye shields are blacked out, replaced with darkly tinted lenses, and it is left unadorned save for the bronze trim of the shoulders and the aquila on the chestplate. As the stone-ceramite coat dries, it cracks and weathers, giving the armor an authentically "stony" look. In a sense, the Stonehides who wear this armor literally have hides of stone.
Warhammer 40,000 belongs to Games Workshop
Stonehides, artwork (c)

Have him stand still, and he'd look like a statue. O_O Bloody brilliant, all around.
p.s. For The Emperor!
Where is there more information?