Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Chordoma ?
    ### Response:
    A chordoma is a rare tumor that develops from cells of the notochord, a structure that is present in the developing embryo and is important for the development of the spine. The notochord usually disappears before birth, though a few cells may remain embedded in the bones of the spine or at the base of the skull.
    