Chelonibia is a genus of acorn barnacles in the family Chelonibiidae of the subphylum Crustacea.

[1] Its members are epizootic and live attached to manatees, turtles, marine molluscs, crabs and horseshoe crabs in all tropical and subtropical oceans.

[2] In a few instances, they have been found on sea snakes,[3] alligators[4] and inanimate substrates,[5] but they are not found in the typical habitats of barnacles – on rocks, docks or boats.

[6] The fossil record of Chelonibia ranges back to the Miocene.

Depending on the host species, they develop plastically very distinct morphology but cannot be distinguished on the genetic level.