Spirochaetes are tightly coiled up bacteria. Filamentous Bacteria are friendly creatures, you never find one bacteria on its own. They tend to live together in clumps, chains or planes. When they live in chains, one after the other, they are called filamentous bacteria - these often have long thin cells. When they tend to collect in a plane or a thin layer over the surface of an object they are called a biofilm.
Many bacteria exist as a biofilm and the study of biofilms is very important.
Biofilm bacteria secrete sticky substances that form a sort of gel in which they live. The plaque on your teeth that causes tooth decay is a biofilm. It is part of the human condition that we tend to be consciously aware of those few bacteria that are pathogens whilst ignoring all those useful species without which life would not be possible. It is important to realise that many, many more bacteria are involved in interactions that are beneficial to the other party than in interactions that are harmful. Some of these cause disease, but others help us digest our food.