3. (Zo["o]l.) Any small calcareous or siliceous body found in
the tissues of various invertebrate animals, especially in
sponges and in most Alcyonaria.
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.
Description of the Illustration:
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.