Lunule
From BiblePortal Wikipedia
Lunule [1]
(1): ( n.) A special area in front of the beak of many bivalve shells. It sometimes has the shape of a double crescent, but is oftener heart-shaped. See Illust. of Bivalve.
(2): ( n.) A small or narrow crescent.
(3): ( n.) A lune. See Lune.
(4): ( n.) Anything crescent-shaped; a crescent-shaped part or mark; a lunula, a lune.