Malleus

n. pl. Mallei (#).
  1. (Anat.) The outermost of the three small auditory bones, ossicles; the hammer. It is attached to the tympanic membrane by a long process, the handle or manubrium. See Illust. of Far.
  2. (Zoöl.) One of the hard lateral pieces of the mastax of Rotifera. See Mastax.
  3. (Zoöl.) A genus of bivalve shells; the hammer shell.