Harmonix is a sub-transformation rather than a full transformation. Enchantix is considered a full transformation. Harmonix is the transformation before Sirenix
This sub power is not supposed to be earned by acheiving a certain accomplishment. It is given by thier sirenix guardians when completing the quest for finding the magical creature that supossevely looks like a uniconrn with rainbow colored hair.
It only shows itself to ones this creature accepts it's wisdom.
A mini dress. they have a tail behind thier dresses to resemble aquatic and ocean-like looks. Thier hair looks somelike Princess Jasmines hair from Disney Princess, only with a fewer hairties.(or a lot fewer than you can imagine). they wear high heels with ribbon straps that come up to thier knees. Some wear seashell hair-pieces that also resemble the ocean. If you have noticed, thier skirts look like seashells. So do their wings.