Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Urachal cyst ?
    ### Response:
    Urachal cyst is a sac-like pocket of tissue that develops in the urachus, a primitive structure that connects the umbilical cord to the bladder in the developing baby. Although it normally disappears prior to birth, part of the urachus may remain in some people.
    