What word signals a nonrestrictive clause in a complex sentence

In the space below, write a 1000-word essay presenting information about an author’s style. reference the author’s work as well as other researched sources. a successful essay will be focused on one specific aspect of the author’s style, give three references to the author’s work, give three references to other sources, and use correct citations.

Can someone me answer this english question

There is nothing miniscule about our --let alone our universe.