Editorial: From sand to shrimps: A tribute to Professor Jason A. C. Gallas

This Focus Issue is a tribute to Jason A. C. Gallas and his outstanding career as a scientist. Gallas coined the term "shrimps" to name ubiquitous structures found in parameter space, and which are now known to exist in many nonlinear systems. His work impacted several fields, ranging from climate and geophysics to quantum optics and medicine. The contributions to the issue include both the theoretical topics Gallas worked on, and the applied fields he approached during his scientific career and which, in the future, will continue being impacted by his work.