Nucella ostrina rest and feed in harmony on their rocky mid and high intertidal grounds. You hardly ever find a loner. Harmony in Nucella, however, could mean a sight of wreckage for acorn barnacles, Balanus glandula. Nucella drills the shells of mussels and barnacles and eats the soft tissue within.
It may be a breach of etiquette to post what might be a violent predator-prey scene in a harmony-themed challenge, but from the Nucella point of view, I see harmony.