The image is a black and white illustration of a chunk of concrete. The concrete is irregularly shaped, with a rough, fractured surface. It appears to be a close-up view, highlighting the texture and composition of the material. The concrete is riddled with numerous small, circular voids or air pockets, giving it a porous appearance. There's also a larger, oval-shaped void visible towards the top left of the image. The overall tone is grayscale, with varying shades of gray representing the different textures and depths of the concrete. Below the image, the text 'FIG. 3. CONCRETE' is printed.