Living organisms exhibit remarkable adaptability through distributed actuation and continuous deformation, thereby inspiring new paradigms in soft robotics. This paper presents a family of bioinspired heterogeneous soft modular robotic cubes designed to reproduce such adaptive mechanisms through coordinated pneumatic actuation. Each module combines elastomeric materials with inextensible fiber patterns that emulate muscular architectures, guiding deformation under pressurization. A hyperelastic Finite Element Analysis (FEA) framework was developed to predict deformation modes and experimentally validated using ultraviolet marker tracking. The modules exhibited diverse motions, including axial expansion, twist, bending, and shear, with close agreement between simulations and experiments. When assembled into a Cartesian soft platform, the modules demonstrated coordinated multi-axis movement. These results highlight the potential of bioinspired modular soft robots as scalable building blocks for robotic systems that bridge natural morphologies with engineered functionality, with the observed secondary couplings suggesting a pathway toward adaptive or reconfigurable behavior in future closed-loop implementations.