Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Gallstones ?
    ### Response:
    Gallstones are hard particles that develop in the gallbladder. The gallbladder is a small, pear-shaped organ located in the upper right abdomenthe area between the chest and hipsbelow the liver.
                
Gallstones can range in size from a grain of sand to a golf ball.
    