The appositive phrases in the sentences above are the following ones: Michelle and a type of root vegetable.
Explanation:
An appositive is a noun or noun phrase that renames another noun right beside it. A nonessential appositive is always separated from the rest of the sentences with commas because it provides information which is not considered necessary to complete the meaning of the sentence. If dropped, the meaning of the sentence would be left unchanged (see A and B).
This centerpiece was called the Orchestra, or the Dancing place. This is where action took part. Later, they added the Proskenion, an area specifically made for acting.