ossicle

noun

1. anatomyA small bone (or bony structure), especially one of the three of the middle ear.

   “The incus is one of the three auditory ossicles.”

2. zoologyBone-like joint or plate, especially:

3. One of numerous small calcareous structures forming the skeleton of certain echinoderms, as the starfishes;

4. One of the hard articuli or joints of the stem or branches of a crinoid or encrinite;

5. One of the several small hard chitinous parts or processes of the gastric skeleton of crustaceans, as in the stomach of a lobster or crawfish.

6. The skeleton of echinoderms is made of ossicles, linked to each other via muscles and connective tissue.