Why? - The signal starts in a receptor which detects a change. Relay neurones carry nerve impulses within the central nervous system. Motor neurones carry nerve impulses away from the central nervous system. The neurone ends in either a muscle or gland, which are effectors.
Eventually, in theory, black holes will evaporate through Hawking radiation. But it would take much longer than the entire age of the universe for most black holes we know about to significantly evaporate.
***more closely related to Eukaryotes than to bacteria, cells walls without peptidoglycan, found in harsh environments, subdivided into 3 groups based on their habitat (methanogens, thermoacidophiles, and extreme halophiles)