Source : Webster's Revised Unabridged Dictionary (1913)

Coquilla nut \Co*quil"la nut\ [Pg. coquilho, Sp. coquillo, dim.
   of coco a cocoanut.] (Bot.)
   The fruit of a Brazilian tree ({Attalea funifera} of
   Martius.).

   Note: Its shell is hazel-brown in color, very hard and close
         in texture, and much used by turners in forming
         ornamental articles, such as knobs for umbrella
         handles.

Source : WordNet®

coquilla nut
     n : nut having a hard hazel-brown shell used like vegetable
         ivory