An endospore's a dormant, tough, and non-reproductive structure produced by Gram-positive bacteria from the Firmicute phylum which forms when a bacterium produces a thick internal wall that encloses its DNA and part of its cytoplasm. Examples include Bacillus and Clostridium. The primary function of most endospores's to ensure the survival of a bacterium through periods of environmental stress. They're therefore resistant to ultraviolet and gamma radiation, desiccation, lysozyme, temperature, st… (More on Endospore)