How does a biological system produce long time scales that vastly outlast intrinsic biochemical rates, yet are not infinite? This challenge features in various biological tasks involving memory and sensing. We uncover how this also manifests in the cellular assembly of a C. elegans embryo. High-resolution imaging reveals that the formation of the cell’s actin cortex is preceded by a stage where thousands of highly branched actin structures transiently grow and disassemble [1]. Many structures grow orders of magnitude past intrinsic degradation time scales before disassembling, yet without proliferating. We uncover how an overlooked bifurcation in the underlying biochemical dynamics can account for this huge lifetime disparity. We find that a simple mechanism based on resource competition can guide the system towards this dynamical bifurcation without the need for parameter fine-tuning or a biological regulatory mechanism. If time allows I will mention

[1] Victoria Tianjing Yan, Arjun Narayanan, Tina Wiegand, Frank Jülicher, Stephan W. Grill, Nature (2022).