Source : Webster's Revised Unabridged Dictionary (1913)

Glass-sponge \Glass"-sponge`\, n. (Zo["o]l.)
   A siliceous sponge, of the genus {Hyalonema}, and allied
   genera; -- so called from their glassy fibers or spicules; --
   called also {vitreous sponge}. See {Glass-rope}, and
   {Euplectella}.