Final answer:
Biofilm masses first develop during the initial attachment stage, where bacteria adhere to surfaces using weak van der Waals interactions, followed by irreversible attachment through pili.
Step-by-step explanation:
Biofilm masses initially develop in what is known as the initial attachment stage, where bacteria adhere to a solid surface using weak van der Waals interactions. This occurs before progressing to irreversible attachment, where cellular appendages called pili permanently anchor the bacteria. The process continues through maturation phases, eventually leading to dispersal, where parts of the biofilm break away to colonize new surfaces. Biofilms can cause a range of problems, from clogging pipes to contributing to antibiotic resistance due to their persistence and protection of the microbial community within them.