Culture medium devices and systems are shown and described. In one embodiment a growth plate includes an upper surface, a recessed well, a raised platform having an opposing cavity, and raised extensions having an opposing receiving aperture. Typically, the well is recessed below the top surface and the platform is above the upper surface. A growth plate assembly typically includes at least a first growth plate's raised stacking surfaces being temporarily received by a second growth plate's receiving surfaces, thereby temporarily securing growth plates together.