Final answer:
Bacteria that produce a heat and drying resistant capsule are forming an endospore, which is a defensive mechanism to survive in adverse environmental conditions.
Step-by-step explanation:
The capsule formed by some bacteria that is resistant to heat and drying is called an Endospore. Bacteria produce endospores as a defensive strategy against unfavorable environmental conditions. The polysaccharide capsule is different from the endospore, serving mainly to help bacteria attach to surfaces and evade the immune system. It's important to note that other structures like flagella, pili, and plasmids serve different purposes such as movement, genetic exchange, and horizontal gene transfer respectively.