Codex: Chaos Space Marines (2002), p27 — Obliterator Cult

Obliterators have dwelt too long in the Eye of Terror and have contracted a contagion that sears the flesh to their armour. Marine and armour become one entity, growing down the centuries into hulking, weirdly baroque leviathans able to reshape their forms to spew death at their enemies. Obliterators are no longer even Chaos Space Marines instead they are an amalgam of Marine, Daemon and Armour, each part inseparable from the rest.