When scientists at the Institute of Science and Technology (IST) Austria looked at developing zebrafish embryos, they observed an abrupt and dramatic change: within just a few minutes, the solid-like embryonic tissue becomes fluid-like. What could cause this change and, what is its role in the further development of the embryo? In a multidisciplinary study published in the journal Cell, they found answers that could change how we look at key processes in development and disease, such as tumor metastasis.