velella

‖n. [ NL., dim. from L. velum a veil, a sail. ] (Zool.) Any species of oceanic Siphonophora belonging to the genus Velella. [ 1913 Webster ]

☞ These creatures are brilliantly colored and float at the surface of the sea. They have an oblong, disklike body, supported by a thin chitinous plate, from which rises a thin diagonal crest which acts as a sail. The feeding and reproductive zooids hang down from the under side of the disk. [ 1913 Webster ]