spicule
    n 1: small pointed structure serving as a skeletal element in
         various marine and freshwater invertebrates e.g. sponges
         and corals [syn: spicule, spiculum]

Spicule \Spic"ule\, n. [L. spiculum a little point, a dart.]
   1. A minute, slender granule, or point.
      [1913 Webster]

   2. (Bot.) Same as Spicula.
      [1913 Webster]

   3. (Zool.) Any small calcareous or siliceous body found in
      the tissues of various invertebrate animals, especially in
      sponges and in most Alcyonaria.
      [1913 Webster]

   Note: Spicules vary exceedingly in size and shape, and some
         of those found in siliceous sponges are very complex in
         structure and elegant in form. They are of great use in
         classification.
         [1913 Webster]

               Description of the Illustration:
         [1913 Webster]

               a Acerate; b Tricurvate, or Bowshaped; c d
               Hamate; e Broomshaped; f Scepterellate; g
               Spinispirulate; h Inequi-anchorate; i Sexradiate;
               j A Trichite Sheaf; k Six-rayed Capitate; l
               Rosette of Esperia; m Equi-anchorate.
         [1913 Webster]