A kind of pelagic colonial hydroid consisting of a central gastrozooid surrounded by gonozooids and defensive polyps, all hanging from a flattened, circular, chitinous float; a fossil of such a hydroid (now rare). Also (in form Porpita): the genus of chondrophores (family Porpitidae) to which these hydroids belong.
Valid publication of the genus name: Lamarck Système des animaux sans vertèbres (1801) 355, after earlier use as specific epithet, e.g. in Medusa Porpita Linnaeus (1758).
Early 18th century; earliest use found in John Woodward (d. 1728), physician, natural historian, and antiquary. From scientific Latin Porpita from ancient Greek πόρπη brooch, clasp (a reduplicated form from an ablaut variant of the base of πείρειν to pierce, run through) + classical Latin -īta.