The trophozoite of Giardia intestinalis (a.k.a.G. lamblia) lives on the epithelial surface of intestine. The actions of flagella create a suction underneath the two sucking disks which helps the trophozoite to adhere.
The trophozoite in this photo illustrates the shield-shaped body of this parasite, its numerous flagella, two dark-staining nuclei and the outlines of the two sucking disks, and the median axostyles.
This specimen is of G. intestinalis from a laboratory culture. It is much flatter than you would normally see in a fecal smear because it was prepared using a Cytospin apparatus- a type of centrifuge used for spinning down a suspension of cells (such as cultured parasites) onto a glass slide.