which type of bacteria form irregular groups or clusters
Two joined cocci are known a diplococci, while four arranged in a square shape are called a tetrad. The Sarcina genus arrange themselves in groups of eight, in a cube shape. The other common arrangements include a chain of bacteria (known as streptococci) or irregular clusters of bacteria (known as staphylococci). The average size of a coccus bacterium is 0.5 - 1 micrometer.