Complex sentence: There are three core roles and a range of ancillary roles--core roles are often referred to as "pigs" and ancillary roles as "chickens" (after the story The Chicken and the Pig).
Split into simpler sentences: There are three core roles and a range of ancillary roles. Core roles are often referred to as "pigs" and ancillary roles as "chickens" (after the story The Chicken and the Pig).