Describe a material in your own words about the properties, in this case the material are CDs,

Requirement: As homework, in addition to finding and collecting, write descriptively about each object or material without naming it, thoughtfully. You are writing, in your own ways, about the properties of the materials. Descriptions may be scientific, practical, poetic, associative, narrative – anything the student believes is pertinent and is inspired to write.
My material are CDs, so please write some descriptions of CD, but do not name it. My professor will read this homework in class, and let my classmates guess what I bring. And do not mention a specific CD.