Which bone is a part of the skull and not just associated with it? incus stapes vomer hyoid malleus?

The correct answer is "the vomer".

The vomer is described as one of the unpaired facial bones of the human skull. I t's located further within the midsagittal line, and articulates with the sphenoid, the ethmoid, which are the left and right palatine bones, and the left and proper maxillary bones. The vomer bone forms the inferior part of the nasal septum, with the advanced part formed through the perpendicular plate of the ethmoid bone.