The Collaborative International Dictionary
Planoblast
Planoblast \Plan"o*blast\, n. [Gr. ? to wander + -blast.] (Zo["o]l.) Any free-swimming gonophore of a hydroid; a hydroid medusa.
Wiktionary
planoblast
n. (context zoology English) Any free-swimming gonophore of a hydroid; a hydroid medusa.