Chelonibia is a genus of acorn barnacles in the monotypic family Chelonibiidae of the subphylum Crustacea. Its members are epizooic and live attached to manatees, turtles, marine molluscs, crabs and horseshoe crabs in all tropical and subtropical oceans. In a few instances, they have been found on sea snakes, alligators and inanimate substrates, but they are not found in the typical habitats of barnacles – on rocks, docks or boats.