| 1. | a predatory marine gastropod of the family Cassidae, characterized by a thick, heavy shell with a broadened outer lip. |
| 2. | the shell of this animal, often used for making cameos. |
helmet shell
any marine snail of the family Cassidae (subclass Prosobranchia, class Gastropoda), characterized by a large, thick shell with a shieldlike inner lip. An example is the 18-centimetre (7-inch) king helmet (Cassis tuberosa) of the Caribbean.
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