acicula
/əˈsɪkjʊlə/(also aciculus, aciculum) Chiefly Zoology and Botany
noun
A slender spine, prickle, or other needle-like structure; (in polychaete annelids) a chitinous rod forming an internal support for a parapodium.
Origin
Late 18th century. From post-classical Latin acicula, lit. ‘small pin’, alteration or variant of acucula from classical Latin acus needle + -cula.