Hypothetical types of biochemistry in the late 1960s, these machines are often classed as computers (or computer-guided robots) and filed under "silicon-based life", even though the silicon backing matrix of these processors is not nearly as fundamental to their operation as carbon is for "wet life". Arsenic, which is chemically similar to phosphorus, while poisonous for most life forms on Earth, is incorporated into the biochemistry of some organisms. Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes ("Chrysiogenes arsenatis").
Exogenous bacteria of this concept is "bacterial flora," which consists of exogenous bacteria ingested and endogenously colonized during the early stages of life. Bacteria that are part of normal internal ecosystems, also known as bacterial flora, are called "Endogenous Bacteria". A significant amount of prominent diseases are induced by "exogenous bacteria" such as "gonorrhea", "meningitis", "tetanus", and "syphilis." Pathogenic exogenous bacteria can enter a host via cutaneous transmission, inhalation, and consumption. Only a minority of bacteria species cause disease in humans; and many species colonize in the human body to create an ecosystem known as bacterial flora. Bacterial flora is endogenous bacteria,