Ceratobranchial bone that is the most posterior, bilaterally paired ventral pharyngeal arch bone. Ceratobranchial 5 ossifies before ceratobranchials 1-4. In the adult, ceratobranchial 5 is heavily ossified and crescent-shaped with two to three rows of posteromedially directed teeth. The anteroventral tips of ceratobranchials 5 meet medially and are ligamentously joined. [ GOC:mh ORCiD:0000-0001-9114-8737 ]