peronium
/pəˈrəʊnɪəm/Zoology
noun
In certain hydromedusae: a tentacle formed by an extension of the umbrellar ectoderm and lacking mesogloea. Usually in plural.
Origin
Late 19th century; earliest use found in Science. From ancient Greek περόνη fibula, brooch + scientific Latin -ium, apparently after German Mantelspange, lit. ‘cloak pin’.