Some scaly-foot snails near deep-sea hot vents have overlapping foot scales infused with iron sulfide. They secrete sulfur compounds into the scales; iron from vent water diffuses in and reacts, forming tiny mineral crystals.

The result differs by location: black snails from one vent field have iron-infused scales, while white ones from another lack this mineralisation. They are the same species, with different mineral finishes.

A deep-sea snail with iron in its scales

Iron-infused black scaly-foot snail on the left; pale non-mineralised snail on the right — JAMSTEC / University of Tokyo (2019), Figure 1. Kairei iron-infused snail on left; Solitaire non-mineralised snail on right. Original comparison; scale bars retained.

Original research diagram explains how sulfur and environmental iron form minerals in the scales — JAMSTEC / University of Tokyo (2019), Figure 4. Original research schematic of iron-sulfide production in scales.

Scaly-foot snails from different Indian Ocean hydrothermal vent fields — JAMSTEC and collaborators (2026), Figure 1. Original map and photographs of scaly-foot snails from Indian Ocean vent fields.

A deep-sea snail with iron in its scales

Explore related topics