Hyalonema \Hy`a*lo*ne"ma\, n. [NL., fr. Gr. "y`alos glass + ? a thread.] (Zool.) A genus of hexactinelline sponges, having a long stem composed of very long, slender, transparent, siliceous fibres twisted together like the strands of a color. The stem of the Japanese species ({Hyalonema Sieboldii}), called {glass-rope}, has long been in use as an ornament. See {Glass-rope}. [1913 Webster]