Rock Identifier
Polished operculum (“Shiva eye” shell) (Calcium-carbonate shell operculum, commonly from a turban snail (family Turbinidae); not a mineral specimen) — fossil
fossil

Polished operculum (“Shiva eye” shell)

Calcium-carbonate shell operculum, commonly from a turban snail (family Turbinidae); not a mineral specimen

AI-generated identification · may be incorrect

White to cream, glossy, with a distinctive spiral pattern; composed mainly of aragonite (CaCO₃), Mohs hardness about 3–4. It is an organic shell structure, not a crystalline rock, and has no typical mineral cleavage.

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Physical properties

White to cream, glossy, with a distinctive spiral pattern; composed mainly of aragonite (CaCO₃), Mohs hardness about 3–4. It is an organic shell structure, not a crystalline rock, and has no typical mineral cleavage.

Formation & geological history

Formed by a marine snail as a closing plate for its shell; the pictured object appears polished. Its age cannot be determined from the image, and such pieces are commonly modern rather than fossils.

Uses & applications

Used in jewelry, crafts, and as a collectible; historically, some opercula were valued as charms or incense materials.

Geological facts

The spiral pattern gives it the name “Shiva eye” in some markets. Similar-looking opercula come from several marine snail species.

Field identification & locations

Recognize it by its smooth, rounded plate and central spiral; it is commonly sourced from tropical coastal regions and shell markets. It is a biological shell material, not an igneous, sedimentary, or metamorphic rock.

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