Chroococcus minor cells are generally spherical or slightly oval, with individual diameters ranging from 3 to 5 micrometers. They typically form small colonies of 2 to 4 cells, which are embedded in a gelatinous matrix. The cells exhibit a blue-green color due to the presence of phycocyanin and chlorophyll a, pigments that are characteristic of cyanobacteria and essential for photosynthesis.