The S3 is the battalion's operations and training officer. A member of the battalion's command staff, an S3 typically holds the rank of major or lieutenant colonel in the Army. The S3 is also the battalion training officer, ensuring the ongoing military education of the battalion's personnel.
The Apicomplexa (also called Apicomplexia) are a large phylum of parasitic protists. Most of them possess a unique form of organelle that comprises a type of plastid called an apicoplast, and an apical complex structure.
However, many of the protists in the old Sporozoa share certain structural features, in particular an apical complex of microtubules within the cell. These protists have now been grouped in the Apicomplexa, probably the largest and best-known taxon of parasitic protists. There are about 4,000 known species, but this is almost certainly a gross underestimate of the actual number. There are no known fossil apicomplexans. However, the group is a very important part of the living biota. Apicomplexans infect both invertebrates and vertebrates; they may be relatively benign or may cause serious illnesses.