Here are the most likely interpretations of "Ummy," each offering a different kind of "interesting piece." The most fascinating "ummy" piece isn't a thing, but a sound: the humble filler word "um" (and its siblings "uh," "er," "ah").
This is a fascinating, albeit brief, prompt. "Ummy" isn't a standard English word, so it immediately raises questions. You could be referring to one of several things, each of which is interesting in its own right.