The gumboot chiton, a type of mollusk, scrapes algae off rocks with its super tough teeth containing the magnetic mineral magnetite, a type of iron oxide. Fully mineralized chiton teeth are the hardest of all known biominerals and are strong enough to grind down rocks.
So far, scientists only know of a few animals that make magnetite and how they do so is not well understood. To gather clues on how the mollusk deposits the mineral in the cusps of its teeth, researchers studied the transcriptome of their developing teeth. The 20 most prevalent RNA transcripts encoded ferritin, a protein that helps store iron and release it when needed, they reported January 29 in Scientific Reports.
The scientists then surveyed the proteins that were produced in the mineralized cusp and identified 22 specific to that area, including a previously unknown protein that the researchers think may help start the formation of the iron oxide.
M. Nemoto et al., “Integrated transcriptomic and proteomic analyses of a molecular mechanism of radular teeth biomineralization in Cryptochiton stelleri,” Scientific Reports, doi: 10.1038/s41598-018-37839-2, 2019.