Do you know ghouls from goblins and ghosts?
osteoma os·te·o·ma (ŏs'tē-ō'mə)
n. pl. os·te·o·mas or os·te·o·ma·ta (-mə-tə)
A benign tumor composed of bony tissue, often developing on the skull.
small, often solitary bone tumour found mainly on bones of the skull. Osteomas usually appear in late childhood or young adulthood; they are often asymptomatic. They do not become malignant, and treatment (by excision) is necessary only if the tumour interferes with normal functioning.