The Collaborative International Dictionary of English v.0.48:

Spiculum \Spic"u*lum\, n.; pl. Spicula. [L., a little point.]
   (Zool.)
   Same as Spicule.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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