There are two stages in the life cycle of B. mandrillaris: the actively feeding trophozoite stage and the spherical cyst stage.
Trophozoites: The trophozoites range from 12-60 µm in length. The trophozoites can have broad, thick pseudopodia for slow movement or be finger-like for spider-like movement (see image below).
Cysts: The cysts range from 12-30 µm in size. They appear to be composed of three layers: a thin, irregular outer layer, a thick inner layer, and a middle layer composed of amorphous material (see image on the right). The cysts have only one nucleus but are frequently seen with two nucleoli.
