Spherical bacteria, also known as cocci (5 letters) and staph (5 letters), are a type of bacteria that are round in shape. They are typically found in pairs, chains, or clusters, and can range in size from 0.2 to 5 micrometers. Cocci are usually harmless, but some species can cause diseases such as strep throat, meningitis, and pneumonia. Staph bacteria can cause skin infections, food poisoning, and toxic shock syndrome. Both types of bacteria can be treated with antibiotics.