The paper is about the connection between material optimization in dynamics and a novel concept of dynamic materials (DM) defined as inseparable union of a framework and the fluxes of mass, momentum, and energy existing in time dependent material formations. An example of a spatial-temporal material geometry is discussed as illustration of a DM capable of accumulating wave energy. Finding the optimal material layouts in dynamics demonstrates conceptual difference from a similar procedure in statics. In the first case, the original constituents are distributed in space-time, whereas in the second - in space alone. The habitual understanding of a material as an isolated framework has come from statics, but a transition to dynamics brings in a new component - the fluxes of mass, momentum, and energy. Based on Noether theorem, these fluxes connect the framework with the environment into inseparable entity termed dynamic material (DM). The key role of DM is that they support controls that may purposefully change the material properties in both space and time, which is the main goal of optimization.