A resting cell, highly resistant to dessication, heat, and chemical agents; when returned to favorable conditions bacteria reactivated, the spores germinated to produce single vegetative cells.
Two types of spores : they are endospores and exospores.
(1). Endospores : They are formed within the vegetative cell. (inside the cell.)
(2). Exospores : They are formed in either one of the ends of the vegetative cell. ( on the surface of the cell ).