Gregarine (parasitic protozoan) from the gut of an amphipod
Coccidia (Eimeria sp.), which doesn't come up on here, nor does its family. Found in a fecal sample (this is a fecal float at 400x, the other pic is a direct at 100x) of a dove.
The Apicomplexa — also called Apicomplexia — are a large group of parasitic protists, most of which possess a unique organelle, a type of plastid called an apicoplast, and an apical complex structure involved in penetrating a host's cell. They are unicellular, spore-forming, and exclusively parasites of animals. Motile structures such as flagella or pseudopods are present only in certain gamete stages. This is a diverse group including organisms such as the coccidia, gregarines, piroplasms, haemogregarines,...