Necrodermis is the mysterious "living metal" (even though it comes from Greek roots meaning "dead skin") from which Necrons and their constructs are made. It is more resistant to damage than most materials known to the Imperium and is capable of repairing itself to a certain extent -- melta weapons and other "overkill" weapons will put them down for good, but many Imperial Guardsmen have filled Necron Warriors with lasgun holes and knocked them down, only to see them rise up whole.
As a whole, Necrodermis borders between Flak Armour and Carapace Armour. Something analogous to the Eldar's Mesh Armour. Whilst it can take more direct hits from small arms than Flak Armour, heavier weapons like Bolters would most definitely punch through this material (Although it depends on how thick the Necrodermis is). The main catch of course, is that it could self-repair over time as aforementioned.
The shape of a Necrodermis can also be modified at will by its C'tan inhabitant, leading to vast differences between the bodies of each Star God. This also allows the spontaneous formation of cutting and slashing weapons as required.
The material that makes up Necrodermis is the aforementioned living metal. The Necrontyr originally invented living metal for use in constructing their ships. It is most often associated with the skin of the C'tan as well as the bodies of the Necrons and their amazing regenerative abilities.
The hull of all Necron vehicles, including the Necron Monolith and the Necron Pylon, is also made of this living metal, where its adaptive and regenerative capabilities render powerful weapons such as Meltaguns, Multi-meltas and Power Fists almost obsolete.
|Armour of Warhammer 40,000|
|Imperials:||Flak Armour - Carapace Armour - Power Armour (Human Power Armour - Dragon Scale Armour |
Exo-Power Armour - Space Marine Power Armour - Artificer Armour - Aegis Armour - Auramite Armour)
Terminator Armour - Centurion Armour
|Chaos:||Flak Armour - Carapace Armour - Power Armour (Chaos Power Armour - Warp-Forged Armour) |
Chaos Terminator Armour - Fleshmetal Armour
|Asuryani:||Mesh Armour - Aspect Armour - Exarch Armour - Phoenix Armour - Rune Armour|
|Drukhari:||Kabalite Armour - Wychsuit - Incubus Warsuit - Ghostplate Armour|
|Harlequins:||Holo-Suit - Death's Legacy|
|Orks:||Studded Armour - Flak Armour - 'Eavy Armour - Mega Armour|
|Tau:||Kroot Armour - Recon Armour - Combat Armour - Battlesuit - Iridium Armour|
|Necrons:||Necrodermis - Sempiternal Weave|
|Tyranids:||Chitin - Carapace - Armoured Exoskeleton - Armoured Shell|