The Only Iron-Armored Animal on Earth
Found exclusively on the mineral-rich chimneys of Indian Ocean hydrothermal vents, Chrysomallon squamiferum is the only known animal species that incorporates iron into its skeleton.
Its shell consists of three distinct layers: an inner layer of aragonite, a spongy middle organic periostracum that absorbs crushing mechanical shocks, and a hard outer coating of iron sulfides (greigite and pyrite).
Sclerite Scales and Internal Power Plant
Covering its exposed foot are hundreds of overlapping, iron-plated scales called sclerites. These armored plates protect the snail against predatory deep-sea crabs that attempt to crack shells with heavy claws.
The snail does not eat in the traditional sense. It houses billions of sulfur-oxidizing bacteria in an oversized esophageal gland. The bacteria metabolize toxic hydrogen sulfide from vent fluids, generating organic sugars that nourish the host.
The Enormous Abyssal Heart
To pump enough oxygenated blood through its bacterial reactor in low-oxygen vent water, the scaly-foot snail has evolved an enormous cardiovascular system. Its heart accounts for approximately 4% of its total body volume, proportional to a human having a heart the size of a basketball.
It is currently listed as Endangered on the IUCN Red List due to the looming threat of deep-sea hydrothermal seafloor mineral mining.
