show Abstracthide AbstractUniaxial compression induces tissue-like multicellular development in haloarchaea. In this work, we show that haloarchaeal multicellular structures converged to mimic animal and plant features such as morphological, viscoelastic, polarity, and molecular specialization distinct from unicellular lifestyle. A fast-evolving, archaeal tissue-like developmental program contributes to the debate on the requirements for complex multicellularity.