https://phys.org/news/2019-01-marine-bacterium-toxic-metals.html

In humans, reactive oxygen species are linked to ageing and also to diseases such as cancers.

To reduce the toxic effects of iron, a family of proteins called ferritins detoxify and store the metal ions within their football-shaped protein shell, generating a safe but accessible deposit that can be drawn on by the cell when iron in the environment becomes scarce.