Acicula

noun

1. A slender, needlelike part or structure, such as a spine or bristle of certain plants and animals or a crystal of certain minerals.
2. A needle, pin, or bodkin, of wood or bone, used by Roman women as a hair-pin. It was not smaller than an acus (which see), but of inferior material.
3. A spine or prickle of an animal or plant. Also called acicle.
4. A name applied to several genera of gastropods, and retained for the representative genus of the family Aciculidæ, inhabiting Europe. A. fusca is the best-known form.
5. A genus of worms.