hornwrack|ˈhɔːnræk| [f. horn n. + wrack, seaweed cast ashore.] A polyzoon of the genus Flustra, resembling a seaweed in appearance, and of somewhat horny consistency. 1819Pantologia, Flustra, horn-wrack.1888Rolleston & Jackson Anim. Life 234 Broad-leafed Hornwrack (Flustra foliacea).