Same as iron but costs 30% more

Doesn't exist. Some metals can form organometallic complexes (with CO, CN, methyl groups), in which case you get for instance "organic mercury" compounds. Iron can also do that, but that's not what theyre talking about here.

What they mean is "biogenic" iron. The snail precipitates dissolved iron and sulfur in the water to form its shell out of iron sulfide. Its a different physical structure, but chemically similar to iron pyrite (fools gold).

Looks like iron sulfide, pyrite, and greigite in this case.

Highlights from this rabbit hole: "imbricating chitinous sclerites" and "conchiolin".

https://www.marinebio.org/species/scaly-foot-snails/chrysomallon-squamiferum/

https://www.nature.com/articles/s41467-020-15522-3

https://academic.oup.com/biolinnean/article-abstract/114/4/949/2415936

Hazarding a guess, but I think it's referring to something like "the biologically mediated reduction of iron".

organic iron plates, not plates of organic iron.

the plates are generated by an organic process, not out of organic materials.

you can't just remove a word from the context and act as if that doesn't change the meaning.

Wikipedia says it's iron sulfide. I'm not sure that's organic.