"carrier shell" meaning in English

{
  "forms": [
    {
      "form": "carrier shells",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "carrier shell (plural carrier shells)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
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          "source": "w"
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        },
        {
          "kind": "lifeform",
          "langcode": "en",
          "name": "Littorinimorphs",
          "orig": "en:Littorinimorphs",
          "parents": [
            "Gastropods",
            "Mollusks",
            "Animals",
            "Lifeforms",
            "All topics",
            "Life",
            "Fundamental",
            "Nature"
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          "source": "w"
        }
      ],
      "glosses": [
        "Any marine snail of the family Xenophoridae, which cements stones and shell fragments to its own shell."
      ],
      "id": "en-carrier_shell-en-noun-XOfoVm17",
      "synonyms": [
        {
          "word": "mason shell"
        }
      ],
      "wikipedia": [
        "Xenophoridae"
      ]
    }
  ],
  "word": "carrier shell"
}

{
  "forms": [
    {
      "form": "carrier shells",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "carrier shell (plural carrier shells)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English entries with topic categories using raw markup",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with non-redundant non-automated sortkeys",
        "Entries using missing taxonomic name (family)",
        "Entries using missing taxonomic name (species)",
        "en:Littorinimorphs"
      ],
      "glosses": [
        "Any marine snail of the family Xenophoridae, which cements stones and shell fragments to its own shell."
      ],
      "synonyms": [
        {
          "word": "mason shell"
        }
      ],
      "wikipedia": [
        "Xenophoridae"
      ]
    }
  ],
  "word": "carrier shell"
}