The cinnamon plateworm evolved from the ferrumworm when iron levels in the cave went low and feeding became difficult. It split from it's ancestor when it began to use up the remaining iron in the cave resulting in it's ancestor's extinction in the area. It then proceeded to move out of the cave to the more mountainous terrain where the iron was still plentiful. In this area it too out competed it's ancestor.
The mountainous terrain was full of iron, though much was below the surface. The only option was too use it's magnetized claws to burrow to iron where it begins to absorb the iron until it is depleted and it has to move on. Much of the iron it ingests is used to grow it's claws or improve the plating on it's back. The plating on it's back may seem useless as little is able to predate on them, but it their most effective defense against tunnel collapses.