Assertion: gastropod's shell | /r/HasProperty | unique
Facets:
Source sentences:
text: Not only do these scaly-foot gastropods have unique shells, but they can also create metal shields in the form of iron-mineral scales around their feet.
text: They are the only known animals to incorporate iron sulfides into their bodies, and their unique shells have three layers to sustain them against threats such as a dissolving shell or being hunted by crabs.