Ultracold neutrons, with energies around 100 neV, are a quite unique tool for precision physics since they can be stored for hundreds of seconds. At the ILL they are produced and used since more than 20 years. I will present the last key results such as the neutron lifetime and the study of gravity at short distances with gravity bounded quantum states. I will also review pasts and future efforts measuring the neutron electric dipole moment and searching for the mirror world via neutron-mirror neutron oscillation.