Organic-inorganic hybrid ferroelastic materials attract great interest in multiple application scenarios, including data storage, shape memory, actuators, mechanical switches, etc. Despite hybrid molecular ferroelastics being the subject of extensive studies due to their remarkable structural and compositional versatility, hybrid metal halide ferroelastics composed of group IIA metal elements have rarely been reported up to now. Herein, a beryllium (Be)-based hybrid halide ABX