"mask shell" meaning in English

{
  "forms": [
    {
      "form": "mask shells",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "mask shell (plural mask shells)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Littorinimorphs",
          "orig": "en:Littorinimorphs",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Any member of the genus Persona (now Distorsio) of spiral marine shell, having a curiously twisted aperture."
      ],
      "id": "en-mask_shell-en-noun-ced75ta4",
      "links": [
        [
          "Distorsio",
          "Distorsio#Translingual"
        ]
      ]
    }
  ],
  "word": "mask shell"
}

{
  "forms": [
    {
      "form": "mask shells",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "mask shell (plural mask shells)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Entries using missing taxonomic name (genus)",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Littorinimorphs"
      ],
      "glosses": [
        "Any member of the genus Persona (now Distorsio) of spiral marine shell, having a curiously twisted aperture."
      ],
      "links": [
        [
          "Distorsio",
          "Distorsio#Translingual"
        ]
      ]
    }
  ],
  "word": "mask shell"
}