noun
date shell; date mussel
A species of bivalve mollusk (Lithophaga curta) that bores into rocks. Common name in Japanese.
イシマテガイは岩に穴を開けて住む貝です。
The date shell is a shellfish that bores holes in rocks and lives in them.
Katakana spelling is standard for this shellfish name.
Kanji spelling is rare; the word is usually written in kana.
The name likely derives from the shape resembling a date fruit and its rock-boring habit, but the exact origin is uncertain.