Meet The Sea Pangolin: A Vanishingly Rare Thermal-Vent Snail With Iron Scales

[eppur_se_muova]

1. So the scales are made of iron sulfide, not metallic iron ...

The soft tissue core of each sclerite was covered in conchiolin, which was in turn covered with pyrite (FeS2) and greigite (Fe3S4), two forms of iron sulphide (Warén et al., 2003). Its shell was also covered in the same material, making it the only known metazoan to use iron in its skeleton (Yao et al., 2010).

https://academic.oup.com/mollus/article/81/3/322/1087877?

Journos, even in science mags, so often confuse "iron-containing" with "made of iron". Iron sulfides are hard minerals, but not metallic like iron (although greigite is ferrimagnetic, which is interesting).