This question is a continuation of two prior ones.
- How to render much of a world's metal unusable?
- What minerals and metals in particular were vital to the development of early civilization?
The setting of my WIP is by no means Hard Science Fiction, it is Science-Fantasy I refuse to chose between the genre's that I love and sought to incorporate elements of both into my own work.
Because my world is fantastical I want it to have as few fridge logic invoking elements as possible. I don't want to break the audiences' "suspension of disbelief", so everything needs to flow together.
I ask is the following at least semi-plausible and what conceptual holes need to be plugged for it to work assuming that it could work at all.
After the development of higher life forms such as plants and animals, there was another great evolutionary leap forward. Some extremophiles began to leave their caustic pools for a much less hostile environment. These creatures were tenacious and complex, relying upon multiple vectors to attain the energy and raw material that they needed.
One linage evolved to become plant like,the botanicals, they absorbed minerals through a form of chemosynthesis and possessing a special apatite for the metals copper,tin,lead and iron, which were abundant in their birth region They also absorbed light and to a lesser extent heat, to among other things help process their metal diet into a pure state which was then used as both a skeleton and armor.
The other linage evolved to become animal like,the zoologicals, they were far more mobile than the botanicals but were but were less efficient at absorbing nutrients. So they began stealing what they needed from the the florals, the refined metals. This began an evolutionarily arms race between metal phages flora that wouldn't end until around the time that sapient races emerged. The botanical metal phages won the war through over kill, they began to produce a miasma that was powerful enough to kill anything around them, and worse this miasma would bond to pure metal(the very thing that florals bark/skin was composed of). Unable to feed the zoological linage of metal phages went extinct.
The Florals are immotile in their adult and form spread via their germ, which takes the form of airborne mites that would travel vast distance looking for rich metal deposits in which to germinate.
It is do to the evolution of a defensive miasma which the kills everything in its vicinity and contaminates pure metal. That early civilization was prevented from making a significant usage of metal and eventually lead to the development non metallic alternatives.