Page "Apicomplexa" Paragraph 62

All members of this phylum have an infectious stage-the sporozoite-which possess three distinct structures in an apical complex.

The apical complex consists of a set of spirally arranged microtubules ( the conoid ), a secretory body ( the rhoptry ) and one or more polar rings.

Additional slender electron dense secretory bodies ( micronemes ) surrounded by one or two polar rings may also be present.

It is this structure that gives the phylum its name.