perithecium

/ˌpɛrɪˈθiːʃiəm/
noun
  1. A small, flask-shaped structure in certain fungi that contains spores and has an opening at the top.
    • Each perithecium releases spores through a small pore.
    • Under the microscope, the perithecium looked like a tiny flask.
    • The scientist counted the number of perithecia on the leaf surface.