What's The Smallest Unit Of Poetry?

Elisa Gabbert believes she's found it:

"The poneme is the smallest unit able to trigger delight, surprise, recognition, or whatever intellectual frisson is the reason that we go to a poem. It could be as small as a symbol or a sequence of letters – Aram Saroyan’s triple-humped 'm' or the 'ghgh' in “'ighght'—or a cluster of words, or it could extend over multiple lines. But whatever its size, it’s the extractable thing that draws us in and brings us back to the poem."