Shuvallan armor is very unique, and not just due to the fact the they're living creatures. Each armor is grown and shaped over time by the shuvallan shell harvesters, so no two armors are identical. The Shuvalla wear a tight suit that has a sort of vascular system running through it. This system connects to canisters of concentrated minerals and nutrients to feed the armor as it's worn. In this particular armor, the right arm has been replaced with a javelin rifle. This rifle is mainly used for long range hunting, but can be used in battle with other shuvalla. Each tribe has their own style or armors, and each one uses varying levels of old world tech to augment said armors.
Back in the old world, these armors also existed, however these creatures can live for quite a long time. It's rather rare, but old armors can be found living and moving on their own in the wild, mainly in caves with water sources, but sightings on the surface are known to happen. While they're not dangerous on their own, if agitated, they can be quite deadly. These are called "ghost armors" by local tribes.