Cyanobacteria used to be called blue-green alage, however pigments can also be black, yellow, green or red. These bacteria have chlorophyll-like pigments that trap light energy during the process of photosynthesis. When a body of water contains a rich supply of nutrients, cyanobacteria may bloom and the water will become a pea green color and be accompanied by a foul odor. Some species of cyanobacteria can contain toxic substances or heavy metals that are harmful to both fish and humans.
Magnetotactic bacteria create miniature magnets out of molecules and atoms; especially iron that becomes saturated within their surroundings. These bacteria collect the iron atoms and molecules in sacks called magnetosomes. Inside the megnetosomes, a chemical reaction takes place, in which chemical rearrangements will generate the iron mineral magnetite, which has magnetic properties. When the magnetotactic bacteria die and decay, they will leave behind tiny chains of magnetic particles that are encased in layers of rock.
Archaea are another kind of prokaryote, they are also microscopic and unicellular. Many archaea are considered extremophiles because they can be found in very harsh conditions that would kill other creatures such as boiling waters, immensely salty pools and volcanic vents. These extremophiles have a protective layer of molecules and enzymes to help them thrive in these intense conditions. For example, halophiles a type of archaea live in an extremely salty environment. Halophiles are capable of keeping all the fluids from flowing out of their cells by either producing solutes or pulling in solutes, usually potassium chloride, from the outside to create a balance between the inside of the cells and the salty water outside. However, not all archaea are considered extremophiles. Many live in waters with normal temperatures and conditions. They can be found floating alongside algae in the oceans.
Not all bacteria are considered to be harmful. Some bacteria thrive in oil. They break down oil's dangerous chemicals and convert them into substances that are harmless. Ochrobactrum anthropi is used to clean the oceans after an oil spill or a gasoline leak in the soil under a gas station.
Our skin is covered with bacteria that are responsible for forming a protective barrier against harmful bacteria, fungi and other disease causing organisms. Our bodies also have billions of bacteria in our digestive system. These bacteria are responsible for breaking down nutrients into a form our bodies can actually use.