Certainly!
Definition: "Class Archiannelida" refers to a specific group (or class) of animals within the larger category called Annelida. Annelida is a phylum that includes segmented worms, and Archiannelida is one of the classes within this phylum.
In more advanced discussions, you might talk about the characteristics that define Class Archiannelida, such as their body segments, habitat preferences, and their role in marine ecosystems.
While "Class Archiannelida" specifically refers to this group of worms, "archi-" is a prefix meaning "chief" or "principal," used in other contexts (like "archenemy"), but it does not relate to the biological term.
There are no direct synonyms for "Class Archiannelida" since it is a specific scientific term. However, you might refer to it as "a class of segmented worms" in informal contexts.
Since "Class Archiannelida" is a technical term, there are no idioms or phrasal verbs associated with it.