Carrollian Fluids and Spontaneous Breaking of Boost Symmetry Jay Armas1,2,*and Emil Have3,4,? 1Institute for Theoretical Physics and Dutch Institute for Emergent Phenomena, University of Amsterdam, 1090 GL Amsterdam, The Netherlands 2Institute for Advanced Study, University of Amsterdam, Oude Turfmarkt 147, 1012 GC Amsterdam, The Netherlands 3School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, Peter Guthrie Tait road, Edinburgh EH9 3FD, United Kingdom ...