radiole
/ˈreɪdɪəʊl/Zoology
noun
1In a sea urchin: each of the large spines which articulate with the primary tubercles.
2In a fan worm or other tentaculate marine worm: each of the main branches or filaments in the branchial crown.
Origin
Late 19th century; earliest use found in Charles Thomson (1830–1882), naturalist. From post-classical Latin radiolus spine of a fossil echinoid from classical Latin radius + -olus.