Johnny Thunders once wrote, "You can't put your arms around a memory.'' and the song continues, "don't try.'' Yet, when complex morphogenetic movements accompany differentiation, the cellular memory of signaling becomes essential. In this issue of Cell Stem Cell, Gunne-Braden et al. (2020) report a network wrapping its arms around the memory of BMP signaling, a phenomenon known as hysteresis.