The Collaborative International Dictionary of English v.0.48:

Hexactinelline \Hex*ac`ti*nel"line\, a. [From NL.
   Hexactinellin[ae], fr. Gr. "e`x six + a dim. of ?, ?, a ray.]
   (Zool.)
   Belonging to the Hexactinellin[ae], a group of sponges,
   having six-rayed siliceous spicules.
   [1913 Webster]