The structure of disordered materials typically ages, but sometimes also rejuvenates, resulting in intriguing memory properties. Progress in numerical simulations of spin has now enabled replication of such phenomena from simple models. This "News and Views" in Nature Physics aims at introducing the recent work by Baity-Jesi, M. et al. Nat. Phys. https://doi.org/10.1038/s41567-023-02014-6 (2023) : "Memory and rejuvenation effects in spin glasses are governed by more than one length scale".