The Collaborative International Dictionary of English v.0.48:

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]