The Collaborative International Dictionary of English v.0.48:

Spherule \Spher"ule\, n. [L. spherula: cf. F. sph['e]rule.]
   A little sphere or spherical body; as, quicksilver, when
   poured upon a plane, divides itself into a great number of
   minute spherules.
   [1913 Webster]

WordNet (r) 3.0 (2006):

spherule
    n 1: a small sphere