Bacteria produce several types of spores called gonidia, sporangiospores, oidia, conidia, cysts, and endospores.
Endospore formation is characteristic of bacilliform bacteria.
These are highly thick-walled and resistant spores that are formed in response to an adverse environment, presence of harmful waste products, or aging of a bacterial colony.
These are formed within the body of the bacterium by dehydration of the protoplast.
The dehydrated protoplast is called endospore primordium.