The most well studied of these is "Bdellovibrio bacteriovorus", which is found almost exclusively in host dependent growth in nature. In this free swimming attack form after searching for prey using its pili, it burrows through the host outer membrane/ peptidoglycan cell wall and enters the periplasmic space. The "Bdellovibrio" bacterium then forms a structure called a bdelloplast. This bdelloplast is created as the host cell is modified to become spherical in shape. Inside the bdelloplast, the singular large flagellum of the predatory Bdellovibrio is lost. The host cell is then rapidly killed allowing the passage of molecules from the interior of the host cytoplasm through to the periplasm freely, and the periplasm dwelling "Bdellovibrio" to feed. Using some of these molecules the "Bdellovibrio" creates a protective environment by reinforcing the peptidoglycan cell wall of the host in which it now dwells using amidases and transpeptidases. After around 4hrs, depending on ambient temperature, the "Bdellovibrio" has increased in size dramatically through this nourishment. It divides to replicate and then leaves via a final lysis of the host's cell wall and membranes. The newly emerging "Bdellovibrio" use their newly grown powerful flagella to swim away and find the next suitable host. Because of this intermittent bdelloplast stage, and momentary parasitic phase (15-20 mins), "Bdellovibrio" could be considered bacterial predators or parasites.