Endospores are hardy, defensive structures that enable some bacteria to survive harmful environmental conditions, such as starvation, high temperatures, desiccation (drying out), chemical disinfectants and extremes in pH.
Recursive formula is a formula that is used to determine the next term of a sequence using one or more of the preceding terms.
1 An example of something recursive is a computer program that uses the same formula at the end of one line of numbers to create the next line of numbers.  An example of something recursive is an essay that keeps repeating the same ideas over and over again.