Our laboratory focuses on understanding size and shape across scales. Control of growth rates by cells and tissues entails precision, one of the least understood features of Biology. We are approaching this problem by considering growth as a dynamic spatiotemporal process that is started, stopped, and shaped. How are cells and tissues integrating size control over time? What signals are relayed to cells or within cells to measure size? We study how organs reach, recover, and fine-tune their final size during animal development and regeneration. Appropriate growth control is critical for the achievement of correct organ size in these processes. Either extra or deficient growth rates lead to organ functional impairment. Importantly, growth rates can change, suggesting that organ size is measured by cells to set or regain proportionality to body size. We aim to uncover growth principles in vivo by using zebrafish as a model organism, with quantitative biology and biophysics approaches. At a different length scale, but using similar concepts, we are using guanine crystals as a new paradigm to explore growth at the subcellular level, towards a mechanistic understanding of the contribution of organelle morphology into cellular function.