Answer:
Extremophiles are a relatively small category of bacteria that flourish in harsh environments. An example is Picrophilus torridus
Pathogenic bacteria are those that cause diseases.
Eubacteria are categorized into Chlamydias, Cyanobacteria, Gram-positive bacteria, Proteobacteria, and Spirochetes.
Bacteria can be spherical, known as cocci, rod-shaped, called bacilli, and spiral-shaped, referred to as spirilla